Merge branch 'master' of github.com:TREX-CoE/trexio

.github/workflows/actions.yml

@@ -15,7 +15,7 @@ jobs:
 
   get_commit_message:
     name: Get commit message
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     outputs:
       message: ${{ steps.commit_message.outputs.message }}
     steps:
@@ -34,8 +34,8 @@ jobs:
 
   trexio_ubuntu:
 
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
-    name: x86 Ubuntu latest
+    name: x86 Ubuntu 20.04
     needs: get_commit_message
 
     steps:
@@ -52,10 +52,10 @@ jobs:
           ./configure --enable-silent-rules
 
       - name: compile TREXIO
-        run: make -j 2
+        run: make -j2
 
       - name: check TREXIO
-        run: make check
+        run: make -j2 check
 
       - name: create virtual environment
         run: |
@@ -82,13 +82,27 @@ jobs:
           name: pytrexio-source
           path: ./trexio-*.tar.gz
 
-      - name: clean
+      - name: maintainer clean
-        run: make clean
+        run: make maintainer-clean
+
+      - name: reconfigure with clang and AddressSanitizer
+        run: |
+          ./autogen.sh
+          ./configure CC=clang-11 CFLAGS="-O2 -fsanitize=address -fno-omit-frame-pointer" LDFLAGS="-fsanitize=address" --enable-silent-rules
+
+      - name: recompile TREXIO
+        run: make -j2
+
+      - name: recheck TREXIO for memory leaks
+        run: make -j2 check
+
+      - name: maintainer clean
+        run: make maintainer-clean
 
   trexio_macos:
 
-    runs-on: macos-latest
+    runs-on: macos-11
-    name: x86 MacOS latest
+    name: x86 MacOS 11
 
     steps:
       - uses: actions/checkout@v2

.github/workflows/build-wheels.yml

@@ -16,7 +16,7 @@ jobs:
   get_commit_message:
     if: ${{ github.event.workflow_run.conclusion == 'success' }}
     name: Get commit message
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     outputs:
       message: ${{ steps.commit_message.outputs.message }}
     steps:
@@ -39,7 +39,7 @@ jobs:
     if: >-
       contains(needs.get_commit_message.outputs.message, '[wheel build]') ||
       (github.repository == 'TREX-CoE/trexio' && startsWith(github.ref, 'refs/tags/v'))
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     strategy:
       matrix:
         manylinux_tag: [2010_x86_64, 2014_x86_64, 2_24_x86_64]
@@ -152,7 +152,7 @@ jobs:
         working-directory: python
 
       - name: Install Python dependencies
-        run: pip install --upgrade pip setuptools build delocate
+        run: pip install --upgrade pip setuptools build delocate pytest
 
       - name: Build wheel for a given version of CPython
         run: |
@@ -169,7 +169,7 @@ jobs:
         working-directory: python
 
       - name: Test the wheel
-        run: python test_api.py
+        run: pytest -v test_api.py
         working-directory: python/test
 
       - name: Upload produced wheels as artifacts
@@ -182,7 +182,7 @@ jobs:
   publish_wheels:
     name: Publish all wheels on PyPI
     needs: [build_linux_wheels, build_macos_wheels]
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
 
     steps:
       - name: Checkout the branch
@@ -222,7 +222,7 @@ jobs:
 
       #- name: Publish distribution 📦 to Test PyPI
       #  uses: pypa/gh-action-pypi-publish@master
-      # with:
+      #  with:
       #    password: ${{ secrets.TEST_PYPI_API_TOKEN }}
       #    repository_url: https://test.pypi.org/legacy/
           #verbose: true

.github/workflows/gh-pages.yml

@@ -20,7 +20,7 @@ jobs:
         run: sudo apt-get update
 
       - name: install dependencies
-        run: sudo apt-get install emacs26
+        run: sudo apt-get install emacs
 
       # this step is needed to pull the git submodule org-html-themes
       #- name: initialize submodules

.gitignore

@@ -41,6 +41,3 @@ trex.json
 *~
 .*.swp
 /build*
-# output of debian build (debuild)
-libtrexio-*
-libtrexio_*

.gitmodules

@@ -1,6 +1,6 @@
 [submodule "python/examples"]
 	path = python/examples
-	url = git@github.com:TREX-CoE/trexio-tutorials.git
+	url = https://github.com/TREX-CoE/trexio-tutorials.git
 [submodule "docs/org-html-themes"]
 	path = docs/org-html-themes
-	url = git@github.com:fniessen/org-html-themes.git
+	url = https://github.com/fniessen/org-html-themes.git

.pre-commit-config.yaml

@@ -0,0 +1,10 @@
+# See https://pre-commit.com for more information
+# See https://pre-commit.com/hooks.html for more hooks
+repos:
+-   repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v3.2.0
+    hooks:
+    -   id: trailing-whitespace
+    -   id: end-of-file-fixer
+    -   id: check-yaml
+    -   id: check-added-large-files

CMakeLists.txt

@@ -4,7 +4,7 @@ cmake_minimum_required(VERSION 3.16)
 
 # Initialize the CMake project.
 project(Trexio
-	VERSION 2.2.0
+	VERSION 2.3.0
 	DESCRIPTION "TREX I/O library"
 	LANGUAGES C Fortran
 	)
@@ -16,7 +16,7 @@ set(CMAKE_C_STANDARD_REQUIRED ON)
 # Optional configure for developer mode to generate source code from org-mode files.
 option(TREXIO_DEVEL "TREXIO developer mode (for code generation)." OFF)
 
-if(EXISTS "${CMAKE_SOURCE_DIR}/.git/config")
+if(EXISTS "${CMAKE_SOURCE_DIR}/.devel")
   set(TREXIO_DEVEL ON)
   find_package(Python3 REQUIRED)
   if(Python3_FOUND)

ChangeLog

@@ -1,9 +1,35 @@
 CHANGES
 =======
 
+2.3
+---
+
+- Fixed Fortran interface on 32-bit (e.g. i386) architectures
+- Changed the structure of the state group
+- Sparse data type is patched to work with different dimensions
+- Safer cleaning of the output files in TREXIO_TEXT tests
+- The global `state` switch is replaced with `state_id` attribute
+- Added `float buffered` type for vectors like CI/CSF coefficients
+- .git folder is no longer needed to activate TREXIO_DEVEL mode
+- Renamed debian folder into helpers-debian
+- Added trexio_to_bitfield_list functionality
+- Added `trexio_has_group` functionality
+- Added OCaml binding
+- Added spin and energy in MOs
+- Added CSF group
+- Added Cholesky-decomposed two-electron integrals
+- Added Cholesky-decomposed RDMs for Gammcor
+- Added `trexio_flush` functionality
+- Optional compilation `--without-fortran`
+
 2.2
 ---
 
+- Added `dim_readonly` data type for read-only dimensions
+- Added I/O for the CI determinants (lists and coefficients) in #91
+- Merged local and non-local components of pseudopotential integrals in  #89
+- Added QMC components to the format in #89
+- Added debian packaging in #84
 - Added support for Python-ic `with` statements
 - Merged local and non-local pseudopotential integrals  in #86
 - Fixed backwards incompatibility of the `TREXIO_TEXT` back end in #82

Makefile.am

@@ -34,7 +34,11 @@
 
 ACLOCAL_AMFLAGS = -I m4
 CLEANFILES = trexio.mod
+if HAVE_FORTRAN
 BUILT_SOURCES = trexio.mod
+else
+BUILT_SOURCES = 
+endif
 EXTRA_DIST = .git_hash
 
 PACKAGE_VERSION = @PACKAGE_VERSION@
@@ -45,10 +49,13 @@ pkgconfig_DATA = pkgconfig/trexio.pc
 
 # =============== BUILD =============== #
 
-trexio_h = $(srcdir)/include/trexio.h
+trexio_h = include/trexio.h
-trexio_f = $(srcdir)/include/trexio_f.f90
+include_HEADERS = $(trexio_h)
 
-include_HEADERS = $(trexio_h) $(trexio_f)
+if HAVE_FORTRAN
+trexio_f = include/trexio_f.f90
+include_HEADERS += $(trexio_f)
+endif
 
 AM_CPPFLAGS = -I$(srcdir)/src -I$(srcdir)/include
 
@@ -56,7 +63,6 @@ lib_LTLIBRARIES = src/libtrexio.la
 
 
 SOURCES = \
-  $(trexio_h) \
   src/trexio.c \
   src/trexio_private.h \
   src/trexio_s.h \
@@ -75,7 +81,7 @@ ORG_FILES = \
   trex.org
 
 
-src_libtrexio_la_SOURCES = $(SOURCES)
+src_libtrexio_la_SOURCES = $(trexio_h) $(SOURCES)
 
 # Include CMake-related files in the distribution.
 EXTRA_DIST += CMakeLists.txt \
@@ -85,25 +91,6 @@ EXTRA_DIST += CMakeLists.txt \
               cmake/FindTREXIO.cmake
 
 
-# Include files needed to produce the debian package.
-DEB_FILES = \
-  debian/changelog     \
-  debian/compat        \
-  debian/control       \
-  debian/copyright     \
-  debian/patches       \
-  debian/README.Debian \
-  debian/README.md     \
-  debian/rules         \
-  debian/source        \
-  debian/watch
-
-EXTRA_DIST += $(DEB_FILES)
-
-debian_from_dist: $(DEB_FILES) $(SOURCES) $(trexio_h)
-	cp ../trexio-$(PACKAGE_VERSION).tar.gz ../libtrexio_$(PACKAGE_VERSION).orig.tar.gz
-	debuild
-
 # =============== TESTS =============== #
 
 TESTS_C = \
@@ -112,6 +99,7 @@ TESTS_C = \
   tests/io_dset_float_text \
   tests/io_dset_int_text \
   tests/io_dset_sparse_text \
+  tests/io_determinant_text \
   tests/io_safe_dset_float_text \
   tests/io_str_text \
   tests/io_dset_str_text \
@@ -127,6 +115,7 @@ TESTS_C += \
   tests/io_dset_float_hdf5 \
   tests/io_dset_int_hdf5 \
   tests/io_dset_sparse_hdf5 \
+  tests/io_determinant_hdf5 \
   tests/io_safe_dset_float_hdf5 \
   tests/io_str_hdf5 \
   tests/io_dset_str_hdf5 \
@@ -134,17 +123,20 @@ TESTS_C += \
   tests/overwrite_all_hdf5
 endif
 
-TESTS_F = \
+TESTS = $(TESTS_C)
-  tests/test_f
+
+if HAVE_FORTRAN
+TESTS_F = tests/test_f
+TESTS += $(TESTS_F)
+endif
 
-TESTS = $(TESTS_C) $(TESTS_F)
 check_PROGRAMS = $(TESTS)
 
 # specify common LDADD options for all tests
 LDADD = src/libtrexio.la
 
-test_trexio_f = $(srcdir)/tests/trexio_f.f90
+if HAVE_FORTRAN
-CLEANFILES += $(test_trexio_f)
+test_trexio_f = tests/trexio_f.f90
 
 $(test_trexio_f): $(trexio_f)
 	cp $(trexio_f) $(test_trexio_f)
@@ -152,10 +144,16 @@ $(test_trexio_f): $(trexio_f)
 trexio.mod: tests/trexio_f.o
 
 tests_test_f_SOURCES = $(test_trexio_f) tests/test_f.f90
+endif
 
 clean-local:
 	-rm -rf -- *.dir/ *.h5 __pycache__/
 
+# =============== GUIX MANIFEST =============== #
+
+trexio_scm = $(srcdir)/tools/trexio.scm
+EXTRA_DIST += $(trexio_scm)
+
 # =============== DOCUMENTATION =============== #
 
 HTML_TANGLED = docs/index.html            \
@@ -193,9 +191,15 @@ HDF5_CPPFLAGS = @HDF5_CPPFLAGS@
 
 if TREXIO_DEVEL
 
-CLEANFILES += $(SOURCES) $(trexio_f) $(trexio_h) $(HTML_TANGLED) $(htmlizer) .git_hash
+CLEANFILES += $(SOURCES) $(trexio_h) $(HTML_TANGLED) $(htmlizer) .git_hash
 
-BUILT_SOURCES += $(SOURCES) $(trexio_f) $(test_trexio_f)
+BUILT_SOURCES += $(SOURCES) $(trexio_h)
+
+if HAVE_FORTRAN
+CLEANFILES += $(trexio_f)
+BUILT_SOURCES += $(trexio_f) $(test_trexio_f)
+$(trexio_f): $(trexio_h)
+endif
 
 .git_hash: FORCE
 	git log | head -1 | cut -d ' ' -f 2 > .git_hash
@@ -205,10 +209,10 @@ all: .git_hash
 GENERATOR_FILES = $(srcdir)/tools/generator.py \
 		  $(srcdir)/tools/generator_tools.py
 
-$(SOURCES): $(trexio_f)
+$(SOURCES): $(trexio_h)
 src/trexio.c: $(trexio_h)
 
-$(trexio_f): $(ORG_FILES) $(GENERATOR_FILES)
+$(trexio_h): $(ORG_FILES) $(GENERATOR_FILES)
 	cd $(srcdir)/tools && ./build_trexio.sh
 
 $(htmlizer): $(ORG_FILES) $(srcdir)/src/README.org
@@ -225,6 +229,22 @@ cppcheck.out: $(trexio_h)
 	  --language=c --std=c99 -rp --platform=unix64  \
 	  -I../include *.c *.h 2>../$@
 
+#################
+# OCaml binding #
+#################
+
+ocaml/trexio/_build/default/lib/trexio.cma:
+	$(MAKE) -C ocaml/trexio
+
+ocaml: ocaml/trexio/_build/default/lib/trexio.cma
+
+ocaml-install: ocaml/trexio/_build/default/lib/trexio.cma
+	opam install ocaml/trexio
+
+##################
+# Python binding #
+##################
+
 setup_py      = $(srcdir)/python/setup.py
 setup_cfg     = $(srcdir)/python/setup.cfg
 pytrexio_py   = $(srcdir)/python/pytrexio/pytrexio.py
@@ -236,8 +256,9 @@ numpy_i       = $(srcdir)/src/numpy.i
 
 
 python-test: $(TEST_PY)
-	python3 $(TEST_PY)
+	python3 -m pytest -v $(TEST_PY)
 	$(RM) -r -- __pycache__
+	$(RM) -f -- test_file_py.h5 unsafe_test_file_py.h5
 
 python-install: $(pytrexio_py) $(setup_py) $(setup_cfg)
 	cd python && \
@@ -269,12 +290,30 @@ $(numpy_i):
 check-numpy:
 	cd tools && ./check_numpy_i.sh
 
+# Include files needed to produce the debian package.
+DEB_FILES = \
+  helpers-debian/changelog     \
+  helpers-debian/compat        \
+  helpers-debian/control       \
+  helpers-debian/copyright     \
+  helpers-debian/rules         \
+  helpers-debian/source        \
+  helpers-debian/libtrexio0.install \
+  helpers-debian/libtrexio-dev.install \
+  helpers-debian/source        \
+  helpers-debian/README.source 
+
+debian_from_dist: $(DEB_FILES) $(SOURCES) $(trexio_h)
+	cp ../trexio-$(PACKAGE_VERSION).tar.gz ../libtrexio_$(PACKAGE_VERSION).orig.tar.gz
+	debuild
+
+
 CLEANFILES += $(pytrexio_c) \
               $(pytrexio_py) \
               $(trexio_py) \
               python/src/*.c \
               python/src/*.h
 
-.PHONY: cppcheck python-test python-install python-sdist check-numpy FORCE
+.PHONY: cppcheck python-test python-install python-sdist check-numpy FORCE ocaml
 
 endif

README.md

@@ -1,5 +1,6 @@
 
 # TREXIO
+<img src="https://trex-coe.eu/sites/default/files/styles/responsive_no_crop/public/2022-01/TREXIO%20Code.png" width=200>
 
 [![build](https://github.com/TREX-CoE/trexio/actions/workflows/actions.yml/badge.svg)](https://github.com/TREX-CoE/trexio/actions/workflows/actions.yml)
 ![GitHub release (latest by date)](https://img.shields.io/github/v/release/TREX-CoE/trexio)
@@ -9,10 +10,10 @@ TREX library for efficient I/O.
 
 ## Minimal requirements (for users):
 
-- Autotools             (autoconf >= 2.69, automake >= 1.11, libtool >= 2.2)	or	CMake (>= 3.16)
+- Autotools             (autoconf >= 2.69, automake >= 1.11, libtool >= 2.2) or CMake (>= 3.16)
 - C compiler            (gcc/icc/clang)
 - Fortran compiler      (gfortran/ifort)
-- HDF5 library          (>= 1.8)	[optional, recommended for high performance]
+- HDF5 library          (>= 1.8) [optional, recommended for high performance]
 
 
 ## Installation procedure from the tarball (for users):
@@ -34,7 +35,7 @@ TREX library for efficient I/O.
 
 - python3       (>= 3.6)
 - Emacs         (>= 26.0)
-- SWIG          (>= 4.0)
+- SWIG          (>= 4.0)   [required for the Python API]
 
 ## Installation procedure from the GitHub repo clone (for developers):
 
@@ -61,6 +62,48 @@ The aforementioned instructions rely on [Autotools](https://www.gnu.org/software
 
 **Note: when linking against an MPI-enabled HDF5 library one usually has to specify the MPI wrapper for the C compiler by adding, e.g., `-DCMAKE_C_COMPILER=mpicc` to the `cmake` command.**
 
+## Installation procedure for conda users
+
+[![Anaconda-Server Badge](https://anaconda.org/conda-forge/trexio/badges/version.svg)](https://anaconda.org/conda-forge/trexio)
+[![Anaconda-Server Badge](https://anaconda.org/conda-forge/trexio/badges/platforms.svg)](https://anaconda.org/conda-forge/trexio)
+
+The official releases of TREXIO `>2.0.0` are also available via the `conda-forge` channel.
+The pre-compiled stable binaries of `trexio` can be installed as follows:
+
+```
+conda install trexio -c conda-forge
+```
+
+More details can be found in the corresponding [trexio-feedstock](https://github.com/conda-forge/trexio-feedstock).
+Note that both parallel (see `mpi_openmpi` prefix) and serial (`nompi`) variants are provided.
+
+## Installation procedure for Guix users
+
+The official releases of TREXIO `>=2.0.0` can be installed using the
+[GNU Guix](https://guix.gnu.org) functional package manager.
+The [trexio.scm](https://github.com/TREX-CoE/trexio/blob/master/tools/trexio.scm)
+Schema file contains the manifest specification for the `trexio` package.
+It can be installed within the selected `$GUIX_PROFILE` as follows:
+
+```
+guix package \
+	--profile=$GUIX_PROFILE \
+	--cores=<n_cores> \
+	--install-from-file=trexio.scm
+```
+
+## Installation procedure for Spack users
+
+The official releases `>=2.0.0` and the development version of TREXIO can be installed using the
+[Spack](https://spack.io/) package manager.
+The [trexio/package.py](https://github.com/spack/spack/blob/develop/var/spack/repos/builtin/packages/trexio/package.py)
+file contains the Spack specifications required to build different variants of `trexio` library.
+It can be installed as follows
+
+```
+spack install --jobs <n_cores> trexio
+```
+
 ## Compilation without the HDF5 library
 
 By default, the configuration step proceeds to search for the [HDF5 library](https://portal.hdfgroup.org/display/HDF5/HDF5).
@@ -120,6 +163,24 @@ These quantities can be accessed using the corresponding `trexio_[has|read|write
 For more details regarding the installation and usage of the TREXIO Python API,
 see [this page](python/README.md).
 
+The aforementioned instructions are adapted for users installing from the source code distribution (periodically updated).
+In order to install the Python API with the latest changes, follow the developer installation guide and run the following command in the end
+
+```
+make python-install
+```
+
+**Note: this implies that both HDF5 and SWIG are installed and available.
+At the moment, it is not possible to configure the Python API without HDF5 library.**
+
+We rely on the `pytest` package for unit testing. It can be installed via `pip install pytest`. To test the installation, run
+
+```
+make python-test
+```
+
+We highly recommend to use virtual environments to avoid compatibility issues and to improve reproducibility.
+
 
 ## Tutorial
 

cmake/FindTREXIO.cmake

@@ -6,7 +6,7 @@
 #  TREXIO_INCLUDE_DIRS - The TREXIO include directories;
 #  TREXIO_LIBRARIES - The libraries needed to use TREXIO;
 
-# If TREXIO has been installed in a non-standard location, one can set an 
+# If TREXIO has been installed in a non-standard location, one can set an
 # environment variable $TREXIO_DIR in the current shell:
 # $ export TREXIO_DIR=<custom_path>
 # to indicate the prefix used during the TREXIO installation
@@ -45,13 +45,13 @@ set(TREXIO_SEARCH_PATHS
 	/opt
 )
 
-find_path(TREXIO_INCLUDE_DIR 
+find_path(TREXIO_INCLUDE_DIR
-	  NAMES trexio.h 
+	  NAMES trexio.h
 	  HINTS $ENV{TREXIO_DIR}
 	  PATH_SUFFIXES include/trexio include
 	  PATHS ${TREXIO_SEARCH_PATHS}
 	  )
-	        
+
 
 # No need to specify platform-specific prefix (e.g. libtrexio on Unix) or
 # suffix (e.g. .so on Unix or .dylib on MacOS) in NAMES. CMake takes care of that.
@@ -70,8 +70,8 @@ INCLUDE(FindPackageHandleStandardArgs)
 FIND_PACKAGE_HANDLE_STANDARD_ARGS(TREXIO DEFAULT_MSG TREXIO_LIBRARY TREXIO_INCLUDE_DIR )
 MARK_AS_ADVANCED(TREXIO_INCLUDE_DIR TREXIO_LIBRARY)
 
-# Mot setting _INCLUDE_DIR and _LIBRARIES is considered a bug, 
+# Mot setting _INCLUDE_DIR and _LIBRARIES is considered a bug,
 # see https://gitlab.kitware.com/cmake/community/-/wikis/doc/tutorials/How-To-Find-Libraries
 set(TREXIO_LIBRARIES ${TREXIO_LIBRARY})
-set(TREXIO_INCLUDE_DIRS ${TREXIO_INCLUDE_DIR}) 
+set(TREXIO_INCLUDE_DIRS ${TREXIO_INCLUDE_DIR})
 

configure.ac

@@ -2,7 +2,7 @@
 # Process this file with autoconf to produce a configure script.
 
 AC_PREREQ([2.69])
-AC_INIT([trexio],[2.2.0],[https://github.com/TREX-CoE/trexio/issues])
+AC_INIT([trexio],[2.3.0],[https://github.com/TREX-CoE/trexio/issues])
 
 AC_CONFIG_SRCDIR([Makefile.in])
 AC_CONFIG_HEADERS([include/config.h])
@@ -16,11 +16,11 @@ AM_PROG_AR
 LT_PREREQ([2.2])
 LT_INIT
 
-# Activate developer mode when the source is the git repository.
+# Activate developer mode if a dummy file is present (true when cloning the git repository).
 # Otherwise, it is the source distribution and the developer mode should not be activated.
-TEST_IFEXISTS=".git"
+TEST_IFEXISTS=".devel"
-AC_CHECK_FILE([$TEST_IFEXISTS],
+AS_IF([test -f $TEST_IFEXISTS],
-        [enable_maintainer_mode="yes"],
+        [enable_maintainer_mode="yes"]
 )
 
 VERSION_MAJOR=`echo ${PACKAGE_VERSION} | cut -d. -f1`
@@ -50,12 +50,18 @@ AS_IF([test "$ac_cv_prog_cc_c99" = "no"],
       [AC_MSG_ERROR([The compiler does not support C99])])
 AC_PROG_CC_C_O
 
-# Fortran
+
-AC_PROG_FC
+# Fortran API [default: --with-fortran], do not disable in the dev mode
-AC_FC_FREEFORM
+AC_ARG_WITH(fortran, [AS_HELP_STRING([--without-fortran],[do not test and install the Fortran API])], ok=$withval, ok=yes)
-AC_FC_SRCEXT([f90])
+if test "$ok" = "yes"; then
-AC_PROG_FC_C_O
+        AC_PROG_FC
-AC_FC_LIBRARY_LDFLAGS
+        AC_FC_FREEFORM
+        AC_FC_SRCEXT([f90])
+        AC_PROG_FC_C_O
+        AC_FC_LIBRARY_LDFLAGS
+fi
+
+AM_CONDITIONAL([HAVE_FORTRAN],[test "$ok" = "yes"])
 
 # pkg-config
 PKG_PROG_PKG_CONFIG()
@@ -66,6 +72,31 @@ AC_PROG_INSTALL
 AC_PROG_LN_S
 AC_PROG_GREP
 
+# Specific options required with some compilers
+case $FC in
+ *gfortran*)
+      FCFLAGS="$FCFLAGS -fPIC"
+      ;;
+ *flang*)
+      FCFLAGS="$FCFLAGS -fPIC"
+      ;;
+ *ifort*)
+      FCFLAGS="$FCFLAGS -fPIC"
+      ;;
+esac
+
+case $CC in
+  *gcc*)
+        CFLAGS="$CFLAGS -fPIC"
+        ;;
+  *clang*)
+        CFLAGS="$CFLAGS -fPIC"
+        ;;
+  *icc*)
+        CFLAGS="$CFLAGS -fPIC"
+        ;;
+esac
+
 
 ## ---------
 ## Libraries
@@ -144,7 +175,7 @@ AC_TYPE_UINT32_T
 AC_TYPE_UINT64_T
 
 # Checks for library functions.
-AC_FUNC_MALLOC
+# AC_FUNC_MALLOC
 AC_CHECK_FUNCS([memset mkdir strerror])
 
 if test "x$enable_maintainer_mode" == "xyes"; then
@@ -153,6 +184,27 @@ else
   TREXIO_DEVEL=""
 fi
 
+
+AC_ARG_WITH(efence, [AS_HELP_STRING([--with-efence],[use ElectricFence library])], ok=$withval, ok=no)
+if test "$ok" = "yes"; then
+        AC_CHECK_LIB([efence], [malloc])
+        ARGS="${ARGS} efence"
+fi
+
+AC_ARG_ENABLE(malloc-trace, [AS_HELP_STRING([--enable-malloc-trace],[use debug malloc/free])], ok=$enableval, ok=no)
+if test "$ok" = "yes"; then
+        AC_DEFINE(MALLOC_TRACE,"malloc_trace.dat",[Define to use debugging malloc/free])
+        ARGS="${ARGS} malloc-trace"
+fi
+
+AC_ARG_ENABLE(prof, [AS_HELP_STRING([--enable-prof],[compile for profiling])], ok=$enableval, ok=no)
+if test "$ok" = "yes"; then
+        CFLAGS="${CFLAGS} -pg"
+        AC_DEFINE(ENABLE_PROF,1,[Define when using the profiler tool])
+        ARGS="${ARGS} prof"
+fi
+
+
 AM_CONDITIONAL([TREXIO_DEVEL],[test "x$TREXIO_DEVEL" != x])
 
 if test "x${TREXIO_DEVEL}" != "x"; then

debian/changelog

@@ -1,5 +0,0 @@
-libtrexio (2.1.0-1) UNRELEASED; urgency=low
-
-  * Initial release.
-
- -- Evgeny Posenitskiy <posenitskiy@irsamc.ups-tlse.fr>  Wed, 16 Feb 2022 15:07:02 +0100

debian/control

@@ -1,15 +0,0 @@
-Source: libtrexio
-Section: science
-Priority: optional
-Maintainer: Evgeny Posenitskiy <posenitskiy@irsamc.ups-tlse.fr>
-Build-Depends: gfortran, pkg-config, libhdf5-dev, debhelper (>=11~), dh-autoreconf
-Standards-Version: 4.1.4
-Homepage: https://trex-coe.github.io/trexio/
-
-Package: libtrexio
-Architecture: any
-Multi-Arch: foreign
-Depends: ${misc:Depends}, ${shlibs:Depends}
-Description: I/O library for quantum chemistry.
- This Debian binary package was auto-generated by the
- debmake(1) command provided by the debmake package.

debian/rules

@@ -1,9 +0,0 @@
-#!/usr/bin/make -f
-# You must remove unused comment lines for the released package.
-#export DH_VERBOSE = 1
-#export DEB_BUILD_MAINT_OPTIONS = hardening=+all
-#export DEB_CFLAGS_MAINT_APPEND  = -Wall -pedantic
-#export DEB_LDFLAGS_MAINT_APPEND = -Wl,--as-needed
-
-%:
-	dh $@ --with autoreconf

examples.org

@@ -3,7 +3,8 @@
 #+SETUPFILE: docs/theme.setup
 
   
-* Accessing sparse quantities
+* Accessing sparse quantities (integrals)
+
 ** Fortran
   :PROPERTIES:
   :header-args:    :tangle  print_energy.f90
@@ -270,3 +271,83 @@ program print_energy
 
 end program
     #+end_src
+
+
+* Reading determinants
+
+** Fortran
+  :PROPERTIES:
+  :header-args:    :tangle  print_dets.f90
+  :END:
+   
+   #+begin_src f90
+program test
+
+  use trexio
+  implicit none
+  
+  character*(128)           :: filename               ! Name of the input file
+  integer(trexio_exit_code) :: rc                     ! Return code for error checking
+  integer(trexio_t)         :: trex_determinant_file  ! TREXIO file handle
+  character*(128)           :: err_msg                ! Error message
+
+
+  integer*8, allocatable :: buffer(:,:,:)
+  integer(8) :: offset, icount, BUFSIZE
+  integer :: ndet, int64_num, m
+
+  integer :: occ_num_up, occ_num_dn
+  integer, allocatable :: orb_list_up(:), orb_list_dn(:)
+
+  call getarg(1, filename)
+
+  trex_determinant_file = trexio_open(filename, 'r', TREXIO_AUTO, rc)
+  if (rc /= TREXIO_SUCCESS) then
+     call trexio_string_of_error(rc, err_msg)
+     print *, 'Error opening TREXIO file: '//trim(err_msg)
+     stop
+  end if
+  
+  rc = trexio_read_determinant_num(trex_determinant_file, ndet)
+  if (rc /= TREXIO_SUCCESS) then
+     call trexio_string_of_error(rc, err_msg)
+     print *, 'Error reading determinant_num: '//trim(err_msg)
+     stop
+  end if
+  print *, 'ndet', ndet
+
+  rc = trexio_get_int64_num(trex_determinant_file, int64_num)
+  if (rc /= TREXIO_SUCCESS) then
+     call trexio_string_of_error(rc, err_msg)
+     print *, 'Error reading int64_num: '//trim(err_msg)
+     stop
+  end if
+  print *, 'int64_num', int64_num
+
+  BUFSIZE = 1000_8
+  allocate(buffer(int64_num, 2, BUFSIZE))
+  allocate(orb_list_up(int64_num*64), orb_list_dn(int64_num*64))
+
+  offset = 0_8
+  icount = BUFSIZE
+  do while (icount == BUFSIZE)
+    if (offset < ndet) then
+      rc = trexio_read_determinant_list(trex_determinant_file, offset, icount, buffer)
+      offset = offset + icount
+    else
+      icount = 0
+    end if
+    print *, '---'
+    do m=1,icount
+      rc = trexio_to_orbital_list_up_dn(int64_num, buffer(1,1,m), &
+           orb_list_up, orb_list_dn, occ_num_up, occ_num_dn)
+      print '(100(I3,X))', (orb_list_up(1:occ_num_up)), (orb_list_dn(1:occ_num_dn))
+      print *, ''
+    end do
+  end do
+
+  deallocate(buffer, orb_list_dn, orb_list_up)
+
+end
+   #+end_src
+  

helpers-debian/README.source

@@ -0,0 +1,15 @@
+libtrexio for Debian
+-------------------
+
+TREXIO distribution tarballs contain the source code required to build the C
+library and the Fortran module based on the ISO_C_BINDING.
+
+The build system is Autotools and follows the common installation path, i.e.
+./autogeh.sh && ./configure && make && make install
+
+For details about the development version (i.e. compiling from the GitHub
+repository clone) contact the upstream maintainers.
+
+
+ -- Evgeny <posenitskiy@irsamc.ups-tlse.fr>  Tue, 27 Sep 2022 10:34:39 +0200
+

helpers-debian/changelog

@@ -0,0 +1,5 @@
+libtrexio (2.2.1-1) UNRELEASED; urgency=medium
+
+  * Initial release (Closes: #1020772)  
+
+ -- Evgeny <posenitskiy@irsamc.ups-tlse.fr>  Tue, 27 Sep 2022 10:34:39 +0200

helpers-debian/control

@@ -0,0 +1,30 @@
+Source: libtrexio
+Section: science
+Priority: optional
+Maintainer: Evgeny <posenitskiy@irsamc.ups-tlse.fr>
+Build-Depends: debhelper-compat (= 12), 
+               gfortran,
+               pkg-config,
+               libhdf5-dev
+Standards-Version: 4.4.1
+Homepage: https://github.com/TREX-CoE/trexio
+#Vcs-Browser: https://salsa.debian.org/debian/libtrexio
+#Vcs-Git: https://salsa.debian.org/debian/libtrexio.git
+
+Package: libtrexio-dev
+Section: libdevel
+Architecture: any
+Multi-Arch: same
+Depends: libtrexio0 (= ${binary:Version}), ${misc:Depends}
+Description: TREX I/O library for efficient data I/O in quantum chemistry.
+ .
+ This package contains the static C library, C headers 
+ and the Fortran modules necessary for developers.
+ 
+Package: libtrexio0
+Architecture: any
+Multi-Arch: same
+Depends: ${shlibs:Depends}, ${misc:Depends}
+Description: TREX I/O library for efficient data I/O in quantum chemistry.
+ .
+ This package contains the shared C library.

helpers-debian/copyright

@@ -1,11 +1,30 @@
 Format: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
 Upstream-Name: libtrexio
-Source: <url://github.com/TREX-CoE/trexio>
+Upstream-Contact: Evgeny <posenitskiy@irsamc.ups-tlse.fr>
-#
+Source: <https://github.com/TREX-CoE/trexio>
-# Please double check copyright with the licensecheck(1) command.
+
+Files: debian/*
+Copyright: 2022 Evgeny <posenitskiy@irsamc.ups-tlse.fr>
+License: GPL-2+
+ This package is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+ .
+ This package is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ GNU General Public License for more details.
+ .
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <https://www.gnu.org/licenses/>
+ .
+ On Debian systems, the complete text of the GNU General
+ Public License version 2 can be found in "/usr/share/common-licenses/GPL-2".
 
 Files:     .git_hash
            AUTHORS
+           ChangeLog
            Makefile.am
            CMakeLists.txt
            NEWS
@@ -35,6 +54,8 @@ Files:     .git_hash
            tests/io_dset_int_text.c
            tests/io_dset_sparse_hdf5.c
            tests/io_dset_sparse_text.c
+           tests/io_determinant_hdf5.c
+           tests/io_determinant_text.c
            tests/io_dset_str_hdf5.c
            tests/io_dset_str_text.c
            tests/io_num_hdf5.c
@@ -47,6 +68,9 @@ Files:     .git_hash
            tests/open_text.c
            tests/overwrite_all_hdf5.c
            tests/overwrite_all_text.c
+           tests/delete_group_hdf5.c
+           tests/delete_group_text.c
+           tests/pre_close.c
            tests/test_f.f90
            tests/trexio_f.f90
 Copyright: 2020 TREX Center of Excellence
@@ -75,9 +99,6 @@ License:   BSD-3-Clause
  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- .
- On Debian systems, the complete text of the BSD 3-clause "New" or "Revised"
- License can be found in `/usr/share/common-licenses/BSD'.
 
 Files:     Makefile.in
            aclocal.m4
@@ -277,9 +298,6 @@ License:   GPL-3.0+ with autoconf exception
  the same distribution terms that you use for the rest of that
  program.  This Exception is an additional permission under section 7
  of the GNU General Public License, version 3 ("GPLv3").
- .
- On Debian systems, the complete text of the GNU General Public License
- Version 3 can be found in `/usr/share/common-licenses/GPL-3'.
 
 Files:     m4/ax_pkg_swig.m4
 Copyright: 2008 Alan W. Irwin
@@ -331,14 +349,11 @@ License:   GPL-2.0+ with unknown exception *** check multiple exceptions ***
 
 #----------------------------------------------------------------------------
 # Files marked as NO_LICENSE_TEXT_FOUND may be covered by the following
-# license/copyright files.
-
 #----------------------------------------------------------------------------
 # License file: COPYING
- BSD 3-Clause License
  .
- Copyright (c) 2021, TREX Center of Excellence
+ Copyright 2020 TREX Center of Excellence
- All rights reserved.
+ License   BSD-3-Clause
  .
  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are met:
@@ -364,3 +379,4 @@ License:   GPL-2.0+ with unknown exception *** check multiple exceptions ***
  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+

helpers-debian/libtrexio-dev.install

@@ -0,0 +1,4 @@
+usr/include/*
+usr/lib/*/lib*.so
+usr/lib/*/lib*.a
+usr/lib/*/pkgconfig/*

helpers-debian/libtrexio0.install

@@ -0,0 +1 @@
+usr/lib/*/lib*.so.*

helpers-debian/rules

@@ -0,0 +1,21 @@
+#!/usr/bin/make -f
+
+
+# output every command that modifies files on the build system.
+#export DH_VERBOSE = 1
+
+
+# see FEATURE AREAS in dpkg-buildflags(1)
+#export DEB_BUILD_MAINT_OPTIONS = hardening=+all
+
+# see ENVIRONMENT in dpkg-buildflags(1)
+# package maintainers to append CFLAGS
+#export DEB_CFLAGS_MAINT_APPEND  = -Wall -pedantic
+# package maintainers to append LDFLAGS
+#export DEB_LDFLAGS_MAINT_APPEND = -Wl,--as-needed
+
+
+%:
+	dh $@
+
+

m4/ax_lib_hdf5.m4

@@ -257,7 +257,7 @@ HDF5 support is being disabled (equivalent to --with-hdf5=no).
           AC_MSG_WARN([Unable to compile HDF5 test program])
         fi
         dnl Look for HDF5's high level library
-        AC_HAVE_LIBRARY([hdf5_hl], [HDF5_LIBS="-lhdf5_hl $HDF5_LIBS"], [], [])
+        AC_CHECK_LIB([hdf5_hl], [main],[HDF5_LIBS="-lhdf5_hl $HDF5_LIBS"], [], [])
 
         CC=$ax_lib_hdf5_save_CC
         CPPFLAGS=$ax_lib_hdf5_save_CPPFLAGS

ocaml/trexio/.ocamlinit

@@ -0,0 +1,3 @@
+#use "topfind";;
+open Printf;;
+

ocaml/trexio/Makefile

@@ -0,0 +1,9 @@
+default: sources
+	dune build
+
+lib/trexio.ml: ../../trex.json read_json.py src/trexio.ml src/trexio.mli src/trexio_stubs.c
+	./read_json.py
+
+sources: lib/trexio.ml
+
+.PHONY: sources default

ocaml/trexio/README.md

@@ -0,0 +1,9 @@
+# TREXIO OCaml interface
+
+## Building the source code
+
+The hand-written source files are located in the `src` directory. These files contain
+the pieces of code that can't be generated automatically. The source code distributed
+in the OPAM package is generated by the `read_json.py` script, and is written in files
+located in the `lib` directory.
+

ocaml/trexio/dune-project

@@ -0,0 +1,36 @@
+(lang dune 3.1)
+
+(name trexio)
+(version 2.3.0)
+
+(generate_opam_files true)
+
+(source
+ (github trex-coe/trexio_ocaml))
+
+(authors
+  "Anthony Scemama <scemama@irsamc.ups-tlse.fr>"
+  "Evgeny Posenitskiy <posenitskiy@irsamc.ups-tlse.fr>"
+)
+
+(maintainers
+  "Anthony Scemama <scemama@irsamc.ups-tlse.fr>"
+)
+
+(license "BSD-3-Clause")
+
+(documentation "https://trex-coe.github.io/trexio/")
+
+(package
+ (name trexio)
+ (synopsis "Binding for the TREXIO Input/Output library")
+ (description "TREXIO is a file format and library for storing wave functions and integrals for quantum chemistry.")
+ (depends
+  dune
+  (dune-configurator :build)
+  (conf-pkg-config :build))
+ (tags
+  ("Quantum chemistry" "Library"))
+)
+
+; See the complete stanza docs at https://dune.readthedocs.io/en/stable/dune-files.html#dune-project

ocaml/trexio/lib/config/discover.ml

@@ -0,0 +1,22 @@
+module C = Configurator.V1
+
+let () =
+C.main ~name:"trexio" (fun c ->
+let default : C.Pkg_config.package_conf =
+  { libs   = ["-ltrexio"]
+  ; cflags = ["-fPIC"]
+  }
+in
+let conf =
+  match C.Pkg_config.get c with
+  | None -> default
+  | Some pc ->
+     match (C.Pkg_config.query pc ~package:"trexio") with
+     | None -> default
+     | Some deps -> deps
+in
+
+
+C.Flags.write_sexp "c_flags.sexp"         conf.cflags;
+C.Flags.write_sexp "c_library_flags.sexp" conf.libs)
+

ocaml/trexio/lib/config/dune

@@ -0,0 +1,3 @@
+(executable
+ (name discover)
+ (libraries dune-configurator))

ocaml/trexio/lib/dune

@@ -0,0 +1,19 @@
+(library
+ (name            trexio)
+ (public_name     trexio)
+ (foreign_stubs
+  (language c)
+  (names trexio_stubs)
+  (flags (:include c_flags.sexp) "-fPIC"))
+ (c_library_flags (:include c_library_flags.sexp))
+)
+
+(rule
+ (targets c_flags.sexp c_library_flags.sexp)
+ (action  (run ./config/discover.exe)))
+
+(env
+ (dev
+  (flags ))
+ (release
+  (ocamlopt_flags )))

ocaml/trexio/read_json.py

@@ -0,0 +1,659 @@
+#!/usr/bin/env python
+
+import json
+
+json_file = "../../trex.json"
+stubs_file= "trexio_stubs.c"
+ml_file   = "trexio.ml"
+mli_file  = ml_file+"i"
+
+def write_stubs(data):
+
+    with open("src/"+stubs_file,'r') as f:
+        content = f.readlines()
+        index = -1
+        for i, line in enumerate(content):
+          if line.startswith("/**** ****/"):
+             index = i
+             break
+        content_pre  = ''.join(content[:index])
+        content_post = ''.join(content[index:])
+
+    with open("lib/"+stubs_file,'w') as f:
+        f.write(content_pre)
+
+        for group in data:
+            t = """
+CAMLprim value caml_delete_{group}(value file)
+{
+  CAMLparam1(file);
+  trexio_exit_code rc = trexio_delete_{group}( File_val(file) );
+  if (rc == TREXIO_SUCCESS) {
+    CAMLreturn ( Val_unit );
+  } else {
+    caml_failwith(trexio_string_of_error(rc));
+  }
+}
+
+CAMLprim value caml_has_{group}(value file)
+{
+  CAMLparam1(file);
+  trexio_exit_code rc = trexio_has_{group}( File_val(file) );
+  if (rc == TREXIO_SUCCESS) {
+    CAMLreturn ( Val_bool(true) );
+  } else {
+    CAMLreturn ( Val_bool(false) );
+  }
+}
+"""
+            f.write( t.replace("{group}",group) )
+
+            for element in data[group]:
+                t = """
+CAMLprim value caml_has_{group}_{element}(value file)
+{
+  CAMLparam1(file);
+  trexio_exit_code rc = trexio_has_{group}_{element}( File_val(file) );
+  CAMLreturn ( Val_bool(rc == TREXIO_SUCCESS) );
+}
+"""
+                f.write( t.replace("{group}", group)
+                          .replace("{element}", element) )
+
+                # Scalar elements
+                if data[group][element][1] == []:
+
+                    if data[group][element][0] in [ "int", "dim", "index" ]:
+                        t = """
+CAMLprim value caml_read_{group}_{element}(value file)
+{
+  CAMLparam1(file);
+  int64_t result;
+  trexio_exit_code rc = trexio_read_{group}_{element}_64( File_val(file), &result );
+  if (rc == TREXIO_SUCCESS) {
+    CAMLreturn ( Val_int(result) );
+  } else {
+    caml_failwith(trexio_string_of_error(rc));
+  }
+}
+
+CAMLprim value caml_write_{group}_{element}(value file, value data)
+{
+  CAMLparam2(file, data);
+  trexio_exit_code rc = trexio_write_{group}_{element}_64( File_val(file), (int64_t) Int_val(data) );
+  if (rc == TREXIO_SUCCESS) {
+    CAMLreturn ( Val_unit );
+  } else {
+    caml_failwith(trexio_string_of_error(rc));
+  }
+}
+"""
+                        f.write( t.replace("{group}", group)
+                                  .replace("{element}", element)
+                                  .replace("{type}", data[group][element][0]) )
+
+                    elif data[group][element][0] in [ "float" ]:
+                        t = """
+CAMLprim value caml_read_{group}_{element}(value file)
+{
+  CAMLparam1(file);
+  double result;
+  trexio_exit_code rc = trexio_read_{group}_{element}_64( File_val(file), &result );
+  if (rc == TREXIO_SUCCESS) {
+    CAMLreturn ( caml_copy_double(result) );
+  } else {
+    caml_failwith(trexio_string_of_error(rc));
+  }
+}
+
+CAMLprim value caml_write_{group}_{element}(value file, value data)
+{
+  CAMLparam2(file, data);
+  trexio_exit_code rc = trexio_write_{group}_{element}_64( File_val(file), (double) Double_val(data) );
+  if (rc == TREXIO_SUCCESS) {
+    CAMLreturn ( Val_unit );
+  } else {
+    caml_failwith(trexio_string_of_error(rc));
+  }
+}
+"""
+                        f.write( t.replace("{group}", group)
+                                  .replace("{element}", element)
+                                  .replace("{type}", data[group][element][0]) )
+
+                    elif data[group][element][0] in [ "string" ]:
+                        t = """
+CAMLprim value caml_read_{group}_{element}(value file, value max_str_len_in)
+{
+  CAMLparam2(file, max_str_len_in);
+  int32_t max_str_len = Int_val(max_str_len_in);
+  char result[max_str_len];
+  trexio_exit_code rc = trexio_read_{group}_{element}( File_val(file), result, max_str_len);
+  if (rc == TREXIO_SUCCESS) {
+    CAMLreturn ( caml_copy_string(result) );
+  } else {
+    caml_failwith(trexio_string_of_error(rc));
+  }
+}
+
+CAMLprim value caml_write_{group}_{element}(value file, value data)
+{
+  CAMLparam2(file, data);
+  const char* val = String_val(data);
+  trexio_exit_code rc = trexio_write_{group}_{element}( File_val(file), val, (int32_t) strlen(val));
+  if (rc == TREXIO_SUCCESS) {
+    CAMLreturn ( Val_unit );
+  } else {
+    caml_failwith(trexio_string_of_error(rc));
+  }
+}
+"""
+                        f.write( t.replace("{group}", group)
+                                  .replace("{element}", element)
+                                  .replace("{type}", data[group][element][0]) )
+
+                    if data[group][element][0] in [ "dim readonly" ]:
+                        t = """
+CAMLprim value caml_read_{group}_{element}(value file)
+{
+  CAMLparam1(file);
+  int64_t result;
+  trexio_exit_code rc = trexio_read_{group}_{element}_64( File_val(file), &result );
+  if (rc == TREXIO_SUCCESS) {
+    CAMLreturn ( Val_int(result) );
+  } else {
+    caml_failwith(trexio_string_of_error(rc));
+  }
+}
+
+"""
+                        f.write( t.replace("{group}", group)
+                                  .replace("{element}", element)
+                                      .replace("{type}", data[group][element][0].split()[0]) )
+
+                # Array elements
+                else:
+
+                    if data[group][element][0] in [ "float" ]:
+                        t = """
+CAMLprim value caml_read_safe_{group}_{element}(value file_in, value size_max_in)
+{
+  CAMLparam2 ( file_in, size_max_in );
+  CAMLlocal1 ( result );
+
+  trexio_t* file = File_val( file_in );
+  int64_t size_max = (int64_t) Int_val(size_max_in);
+
+  double* read_data = (double*) malloc (size_max * sizeof(double));
+  trexio_exit_code rc = trexio_read_safe_{group}_{element}_64(file, read_data, size_max);
+  if (rc != TREXIO_SUCCESS) {
+     caml_failwith(trexio_string_of_error(rc));
+  }
+
+  result = caml_alloc(size_max * Double_wosize, Double_array_tag);
+  for (size_t i=0 ; i<size_max ; ++i) {
+    Store_double_field( result, i, read_data[i] );
+  }
+  free(read_data);
+
+  CAMLreturn (result);
+}
+
+CAMLprim value caml_write_safe_{group}_{element}(value file_in, value size_max_in, value array)
+{
+  CAMLparam3 ( file_in, size_max_in, array );
+
+  trexio_t* file = File_val( file_in );
+  int64_t size_max = (int64_t) Int_val(size_max_in);
+
+  double* c_array = (double*) malloc (size_max * sizeof(double));
+  for (size_t i=0 ; i<size_max ; ++i) {
+    c_array[i] = Double_field(array, i);
+  }
+
+  trexio_exit_code rc = trexio_write_safe_{group}_{element}_64(file, c_array, size_max);
+  if (rc != TREXIO_SUCCESS) {
+     caml_failwith(trexio_string_of_error(rc));
+  }
+  free(c_array);
+
+  CAMLreturn ( Val_unit );
+}
+
+"""
+                        f.write( t.replace("{group}", group)
+                                  .replace("{element}", element)
+                                  .replace("{type}", data[group][element][0]) )
+
+                    elif data[group][element][0] in [ "int", "index", "dim" ]:
+                        t = """
+CAMLprim value caml_read_safe_{group}_{element}(value file_in, value size_max_in)
+{
+  CAMLparam2 ( file_in, size_max_in );
+  CAMLlocal1 ( result );
+
+  trexio_t* file = File_val( file_in );
+  int64_t size_max = (int64_t) Int_val(size_max_in);
+
+  int64_t* read_data = (int64_t*) malloc (size_max * sizeof(int64_t));
+  trexio_exit_code rc = trexio_read_safe_{group}_{element}_64(file, read_data, size_max);
+  if (rc != TREXIO_SUCCESS) {
+     caml_failwith(trexio_string_of_error(rc));
+  }
+
+  result = caml_alloc(size_max, 0);
+  for (size_t i=0 ; i<size_max ; ++i) {
+    Store_field( result, i, Val_int(read_data[i]) );
+  }
+  free(read_data);
+
+  CAMLreturn (result);
+}
+
+CAMLprim value caml_write_safe_{group}_{element}(value file_in, value size_max_in, value array)
+{
+  CAMLparam3 ( file_in, size_max_in, array );
+
+  trexio_t* file = File_val( file_in );
+  int64_t size_max = (int64_t) Int_val(size_max_in);
+
+  int64_t* c_array = (int64_t*) malloc (size_max * sizeof(int64_t));
+  for (size_t i=0 ; i<size_max ; ++i) {
+    c_array[i] = Int_val( Field(array, i) );
+  }
+
+  trexio_exit_code rc = trexio_write_safe_{group}_{element}_64(file, c_array, size_max);
+  if (rc != TREXIO_SUCCESS) {
+     caml_failwith(trexio_string_of_error(rc));
+  }
+  free(c_array);
+
+  CAMLreturn ( Val_unit );
+}
+
+"""
+                        f.write( t.replace("{group}", group)
+                                  .replace("{element}", element)
+                                  .replace("{type}", data[group][element][0]) )
+
+                    elif data[group][element][0] in [ "string" ]:
+                        t = """
+CAMLprim value caml_read_safe_{group}_{element}(value file_in, value size_max_in, value max_str_len_in)
+{
+  CAMLparam3 ( file_in, size_max_in, max_str_len_in );
+  CAMLlocal1 ( result );
+
+  trexio_t* file = File_val( file_in );
+  int64_t size_max = (int64_t) Int_val(size_max_in);
+  int32_t max_str_len = Int_val(max_str_len_in);
+
+  char** read_data = (char**) malloc (size_max * sizeof(char*));
+  read_data[0] = (char*) malloc (size_max * (int64_t) (max_str_len+1) * sizeof(char));
+  for (size_t i=1 ; i<size_max ; ++i) {
+     read_data[i] = read_data[i-1] + max_str_len+1;
+  }
+  trexio_exit_code rc = trexio_read_{group}_{element}(file, read_data, max_str_len);
+
+  if (rc != TREXIO_SUCCESS) {
+     caml_failwith(trexio_string_of_error(rc));
+  }
+
+  result = caml_alloc(size_max, 0);
+  for (size_t i=0 ; i<size_max ; ++i) {
+    Store_field( result, i, caml_copy_string(read_data[i]) );
+  }
+
+  free(read_data[0]);
+  free(read_data);
+
+  CAMLreturn (result);
+
+}
+
+CAMLprim value caml_write_safe_{group}_{element}(value file_in, value size_max_in, value max_str_len_in, value array)
+{
+  CAMLparam4 ( file_in, size_max_in, max_str_len_in, array );
+
+  trexio_t* file = File_val( file_in );
+  int64_t size_max = (int64_t) Int_val(size_max_in);
+  int32_t max_str_len = Int_val(max_str_len_in);
+
+  char** c_array = (char**) malloc (size_max * sizeof(char*));
+  c_array[0] = (char*) malloc (size_max * (max_str_len+1) * sizeof(char*));
+  for (size_t i=1 ; i<size_max ; ++i) {
+    c_array[i] = c_array[i-1] + max_str_len+1;
+  }
+  for (size_t i=0 ; i<size_max ; ++i) {
+    strcpy(c_array[i], String_val( Field(array, i) ));
+  }
+
+  printf("%d\\n", max_str_len);
+  fprintf(stderr,"%d\\n", max_str_len);
+  trexio_exit_code rc = trexio_write_{group}_{element}(file, (const char**) c_array, max_str_len);
+  if (rc != TREXIO_SUCCESS) {
+     caml_failwith(trexio_string_of_error(rc));
+  }
+  free(c_array[0]);
+  free(c_array);
+
+  CAMLreturn ( Val_unit );
+}
+
+"""
+                        f.write( t.replace("{group}", group)
+                                  .replace("{element}", element)
+                                  .replace("{type}", data[group][element][0]) )
+
+                    if data[group][element][0] in [ "float sparse" ]:
+                        size = len(data[group][element][1])
+                        t = """
+CAMLprim value caml_read_{group}_{element}(value file_in, value offset_in, value buffer_size_in)
+{
+  CAMLparam3 ( file_in, offset_in, buffer_size_in );
+  CAMLlocal2 ( result, data );
+
+  trexio_t* file = File_val( file_in );
+  int64_t offset = Int_val( offset_in );
+  int64_t buffer_size = Int_val( buffer_size_in );
+
+  int64_t size_max = buffer_size;
+  int32_t* index_sparse_read = (int32_t*) malloc ({size}*size_max*sizeof(int32_t));
+  double* value_sparse_read = (double*) malloc (size_max*sizeof(double));
+
+  trexio_exit_code rc = trexio_read_safe_{group}_{element}(file, offset, &buffer_size,
+                                               index_sparse_read, size_max,
+                                               value_sparse_read, size_max);
+
+  if (rc != TREXIO_SUCCESS) {
+     caml_failwith(trexio_string_of_error(rc));
+  }
+
+  result = caml_alloc(buffer_size, 0);
+  for (size_t i=0 ; i<buffer_size ; ++i) {
+    data = caml_alloc_tuple({size}+1);
+    for (int j=0 ; j<{size} ; ++j) {
+      Store_field(data, j, Val_int( index_sparse_read[{size}*i+j] ));
+    }
+    Store_field(data, {size}, caml_copy_double( value_sparse_read[i] ));
+    Store_field(result, i, data);
+  }
+
+  free(index_sparse_read);
+  free(value_sparse_read);
+
+  CAMLreturn(result);
+
+}
+
+
+CAMLprim value caml_write_{group}_{element}(value file_in, value offset_in, value buffer_in)
+{
+  CAMLparam3 ( file_in, offset_in, buffer_in );
+  CAMLlocal1 ( data );
+
+  trexio_t* file = File_val( file_in );
+  int64_t offset = Int_val( offset_in );
+  int64_t buffer_size = Wosize_val( buffer_in );
+  const int64_t size_max = buffer_size;
+
+  int32_t* index_sparse_write = (int32_t*) malloc ({size}*size_max*sizeof(int32_t));
+  double* value_sparse_write = (double*) malloc (size_max*sizeof(double));
+
+  for (size_t i=0 ; i<buffer_size ; ++i) {
+
+    data = Field(buffer_in, i);
+    for (int j=0 ; j<{size} ; ++j) {
+      index_sparse_write[{size}*i+j] = Int_val( Field(data, j) );
+    }
+    value_sparse_write[i] = Double_val( Field(data, {size}) );
+  }
+
+  trexio_exit_code rc = trexio_write_safe_{group}_{element}(file, offset, buffer_size,
+                                               index_sparse_write, size_max,
+                                               value_sparse_write, size_max);
+
+  if (rc != TREXIO_SUCCESS) {
+     caml_failwith(trexio_string_of_error(rc));
+  }
+
+  free(index_sparse_write);
+  free(value_sparse_write);
+
+  CAMLreturn( Val_unit );
+
+}
+
+
+"""
+                        f.write( t.replace("{group}", group)
+                                  .replace("{element}", element)
+                                  .replace("{size}", str(size))
+                                  .replace("{type}", data[group][element][0]) )
+
+        f.write(content_post)
+
+def write_mli(data):
+
+    with open("src/"+mli_file,'r') as f:
+        content = f.readlines()
+        index = -1
+        for i, line in enumerate(content):
+          if line.startswith("(**** ****)"):
+             index = i
+             break
+        content_pre  = ''.join(content[:index])
+        content_post = ''.join(content[index:])
+
+    with open("lib/"+mli_file,'w') as f:
+        f.write(content_pre)
+
+        for group in data:
+            t  = "val delete_{group}: trexio_file -> unit\n"
+            t += "val has_{group}: trexio_file -> bool\n"
+            f.write( t.replace("{group}",group) )
+
+            for element in data[group]:
+                t = "val has_{group}_{element}: trexio_file -> bool\n"
+                f.write( t.replace("{group}", group)
+                          .replace("{element}", element) )
+
+                # Scalar elements
+                if data[group][element][1] == []:
+
+                    if data[group][element][0] in [ "int", "float", "dim", "index" ]:
+                        t = [ "val read_{group}_{element} : trexio_file -> {type}\n" ,
+                              "val write_{group}_{element}: trexio_file -> {type} -> unit\n" ]
+                        for i in t:
+                            f.write( i.replace("{group}", group)
+                                      .replace("{element}", element)
+                                      .replace("{type}", data[group][element][0]) )
+
+                    elif data[group][element][0] in [ "string" ]:
+                        t = [ "val read_{group}_{element} : ?max_str_len:int -> trexio_file -> {type}\n" ,
+                              "val write_{group}_{element}: trexio_file -> {type} -> unit\n" ]
+                        for i in t:
+                            f.write( i.replace("{group}", group)
+                                      .replace("{element}", element)
+                                      .replace("{type}", data[group][element][0]) )
+
+                    elif data[group][element][0] in [ "dim readonly" ]:
+                        t = [ "val read_{group}_{element} : trexio_file -> {type}\n" ]
+                        for i in t:
+                            f.write( i.replace("{group}", group)
+                                      .replace("{element}", element)
+                                      .replace("{type}", data[group][element][0].split()[0]) )
+
+                # Arrays
+                else:
+
+                    if data[group][element][0] in [ "int", "float", "dim", "index" ]:
+                        t = [ "val read_safe_{group}_{element} : trexio_file -> int -> {type} array\n" ,
+                              "val write_safe_{group}_{element}: trexio_file -> int -> {type} array -> unit\n"
+                              "val read_{group}_{element} : trexio_file -> {type} array\n" ,
+                              "val write_{group}_{element}: trexio_file -> {type} array -> unit\n"
+]
+                        for i in t:
+                            f.write( i.replace("{group}", group)
+                                      .replace("{element}", element)
+                                      .replace("{type}", data[group][element][0]) )
+
+                    elif data[group][element][0] in [ "string" ]:
+                        t = [ "val read_safe_{group}_{element} : trexio_file -> int -> int -> {type} array\n" ,
+                              "val write_safe_{group}_{element}: trexio_file -> int -> int -> {type} array -> unit\n"
+                              "val read_{group}_{element} : ?max_str_len:int -> trexio_file -> {type} array\n" ,
+                              "val write_{group}_{element}: trexio_file -> {type} array -> unit\n"
+]
+                        for i in t:
+                            f.write( i.replace("{group}", group)
+                                      .replace("{element}", element)
+                                      .replace("{type}", data[group][element][0]) )
+
+                    elif data[group][element][0] in [ "float sparse" ]:
+                        size = len(data[group][element][1])
+                        typ = "(" + "*".join( [ "int" for _ in range(size) ]) + " * float) array"
+                        t = [ "val read_{group}_{element} : trexio_file -> offset:dim -> buffer_size:dim -> {type}\n" ,
+                              "val write_{group}_{element} : trexio_file -> offset:dim -> {type} -> unit\n" ,
+                            ]
+                        for i in t:
+                            f.write( i.replace("{group}", group)
+                                      .replace("{element}", element)
+                                      .replace("{type}", typ) )
+
+        f.write(content_post)
+
+
+def write_ml(data):
+
+    with open("src/"+ml_file,'r') as f:
+        content = f.readlines()
+        index = -1
+        for i, line in enumerate(content):
+          if line.startswith("(**** ****)"):
+             index = i
+             break
+        content_pre  = ''.join(content[:index])
+        content_post = ''.join(content[index:])
+
+    with open("lib/"+ml_file,'w') as f:
+        f.write(content_pre)
+
+        for group in data:
+            t  = "external delete_{group}: trexio_file -> unit = \"caml_delete_{group}\"\n"
+            t += "external has_{group}: trexio_file -> bool = \"caml_has_{group}\"\n"
+            f.write( t.replace("{group}",group) )
+
+            for element in data[group]:
+                t = "external has_{group}_{element}: trexio_file -> bool = \"caml_has_{group}_{element}\"\n"
+                f.write( t.replace("{group}", group)
+                          .replace("{element}", element) )
+
+                # Scalar elements
+                if data[group][element][1] == []:
+
+                    if data[group][element][0] in [ "int", "float", "dim", "index" ]:
+                        t = [ "external read_{group}_{element} : trexio_file -> {type} = \"caml_read_{group}_{element}\"\n" ,
+                              "external write_{group}_{element}: trexio_file -> {type} -> unit = \"caml_write_{group}_{element}\"\n" ]
+                        for i in t:
+                            f.write( i.replace("{group}", group)
+                                      .replace("{element}", element)
+                                      .replace("{type}", data[group][element][0]) )
+
+                    if data[group][element][0] in [ "string" ]:
+                        t = [ "external read_{group}_{element}_c : trexio_file -> int -> {type} = \"caml_read_{group}_{element}\"\n" ,
+                              "let read_{group}_{element} ?(max_str_len=8192) f = read_{group}_{element}_c f max_str_len\n",
+                              "external write_{group}_{element}: trexio_file -> {type} -> unit = \"caml_write_{group}_{element}\"\n" ]
+                        for i in t:
+                            f.write( i.replace("{group}", group)
+                                      .replace("{element}", element)
+                                      .replace("{type}", data[group][element][0]) )
+
+                    elif data[group][element][0] in [ "dim readonly" ]:
+                        t = [ "external read_{group}_{element} : trexio_file -> {type} = \"caml_read_{group}_{element}\"\n" ]
+                        for i in t:
+                            f.write( i.replace("{group}", group)
+                                      .replace("{element}", element)
+                                      .replace("{type}", data[group][element][0].split()[0]) )
+
+                # Arrays
+                else:
+
+                    if data[group][element][0] in [ "int", "float", "dim", "index" ]:
+                        t = [ "external read_safe_{group}_{element} : trexio_file -> int -> {type} array = \"caml_read_safe_{group}_{element}\"\n" ,
+                              "external write_safe_{group}_{element}: trexio_file -> int -> {type} array -> unit = \"caml_write_safe_{group}_{element}\"\n",
+                               "let read_{group}_{element} f = \n  let size = 1 in \n"]
+                        t_prime = []
+                        for dim in data[group][element][1]:
+                            try:    # A dimensioning variable
+                              dim_group, dim_element = dim.split('.')
+                              t_prime += [f"  let size = size * read_{dim_group}_{dim_element} f in\n"]
+                            except: # Only an integer
+                              t_prime += [f"  let size = size * {dim} in\n"]
+
+                        t += t_prime
+                        t += [ "  read_safe_{group}_{element} f size\n\n" ]
+                        t += [ "let write_{group}_{element} f a = \n  let size = 1 in \n"]
+                        t += t_prime
+                        t += [ "  write_safe_{group}_{element} f size a\n\n" ]
+                        for i in t:
+                            f.write( i.replace("{group}", group)
+                                      .replace("{element}", element)
+                                      .replace("{type}", data[group][element][0]) )
+
+                    elif data[group][element][0] in [ "string" ]:
+                        t = [ "external read_safe_{group}_{element} : trexio_file -> int -> int -> {type} array = \"caml_read_safe_{group}_{element}\"\n" ,
+                              "external write_safe_{group}_{element}: trexio_file -> int -> int -> {type} array -> unit = \"caml_write_safe_{group}_{element}\"\n",
+                               "let read_{group}_{element} ?(max_str_len=1024) f = \n  let size = 1 in \n"]
+                        t_prime = []
+                        for dim in data[group][element][1]:
+                            try:    # A dimensioning variable
+                              dim_group, dim_element = dim.split('.')
+                              t_prime += [f"  let size = size * read_{dim_group}_{dim_element} f in\n"]
+                            except: # Only an integer
+                              t_prime += [f"  let size = size * {dim} in\n"]
+
+                        t += t_prime
+                        t += [ "  read_safe_{group}_{element} f size max_str_len\n\n" ,
+                               "let write_{group}_{element} f a = \n  let size = 1 in \n",
+                               "  let max_str_len = Array.map String.length a\n" ,
+                               "      |> Array.fold_left (fun x y -> if x>y then x else y) 0\n",
+                               "      |> (+) 1 in\n" ]
+                        t += t_prime
+                        t += [ "  write_safe_{group}_{element} f size max_str_len a\n\n" ]
+                        for i in t:
+                            f.write( i.replace("{group}", group)
+                                      .replace("{element}", element)
+                                      .replace("{type}", data[group][element][0]) )
+
+
+                    elif data[group][element][0] in [ "float sparse" ]:
+                        size = len(data[group][element][1])
+                        typ = "(" + "*".join( [ "int" for _ in range(size) ]) + " * float) array"
+                        t = [ "external read_{group}_{element} : trexio_file -> offset:dim -> buffer_size:dim -> {type} = \"caml_read_{group}_{element}\"\n" ,
+                              "external write_{group}_{element} : trexio_file -> offset:dim -> {type} -> unit = \"caml_write_{group}_{element}\"\n"
+                            ]
+                        for i in t:
+                            f.write( i.replace("{group}", group)
+                                      .replace("{element}", element)
+                                      .replace("{type}", typ) )
+
+        f.write(content_post)
+
+
+
+
+def main():
+
+    with open(json_file,'r') as f:
+        data = json.load(f)
+        for group in data:
+          for element in data[group]:
+             if data[group][element][0] == "str":
+                  data[group][element][0] = "string"
+
+    write_ml(data)
+    write_mli(data)
+    write_stubs(data)
+
+if __name__ == "__main__":
+    main()
+

ocaml/trexio/src/trexio.ml

@@ -0,0 +1,37 @@
+
+type trexio_file
+
+type trexio_exit_code = int
+
+type trexio_backend =
+| HDF5
+| TEXT
+| AUTO
+
+type index = int
+type dim   = int
+
+external open_file : string -> char -> trexio_backend -> trexio_file = "caml_open_file"
+external close_file : trexio_file -> unit = "caml_close_file"
+external inquire_file : string -> bool = "caml_inquire_file"
+external set_one_based : trexio_file -> unit = "caml_set_one_based"
+external get_state : trexio_file -> int = "caml_get_state"
+external set_state : trexio_file -> int -> unit = "caml_set_state"
+external info : unit -> unit = "caml_info"
+
+external to_orbital_list : Int64.t array -> int list = "caml_to_orbital_list"
+
+
+(**** ****)
+
+external read_determinant_list : trexio_file -> offset:int -> buffer_size:int -> (bytes * bytes) array = "caml_read_determinant_list"
+external write_determinant_list : trexio_file -> offset:int -> (bytes * bytes) array -> unit = "caml_write_determinant_list"
+
+external read_determinant_coefficient : trexio_file -> offset:int -> buffer_size:int -> float array = "caml_read_determinant_coefficient"
+external write_determinant_coefficient : trexio_file -> offset:int -> float array -> unit = "caml_write_determinant_coefficient"
+
+
+let to_orbital_list_up_dn (up,dn) =
+  (to_orbital_list up, to_orbital_list dn)
+
+

ocaml/trexio/src/trexio.mli

@@ -0,0 +1,41 @@
+(*
+(** Constants *)
+val package_version : string
+val version_major   : int
+val version_minor   : int
+val version_patch   : int
+val git_hash        : string
+*)
+
+(** Open/close *)
+
+type trexio_file
+type trexio_exit_code
+type trexio_backend =
+  | HDF5
+  | TEXT
+  | AUTO
+
+type index = int
+type dim   = int
+
+val open_file : string -> char -> trexio_backend -> trexio_file
+val inquire_file : string -> bool
+val close_file : trexio_file -> unit
+val set_one_based : trexio_file -> unit
+val get_state : trexio_file -> int
+val set_state : trexio_file -> int -> unit
+val info : unit -> unit
+
+val to_orbital_list : Int64.t array -> int list
+val to_orbital_list_up_dn : (Int64.t array)*(Int64.t array) -> (int list)*(int list)
+
+(**** ****)
+
+val read_determinant_list : trexio_file -> offset:int -> buffer_size:int -> (bytes * bytes) array
+val write_determinant_list : trexio_file -> offset:int -> (bytes * bytes) array -> unit
+
+val read_determinant_coefficient : trexio_file -> offset:int -> buffer_size:int -> float array
+val write_determinant_coefficient : trexio_file -> offset:int -> float array -> unit
+
+

ocaml/trexio/src/trexio_stubs.c

@@ -0,0 +1,268 @@
+#include <stdio.h>
+#include <trexio.h>
+#include <string.h>
+#define CAML_NAME_SPACE
+#include <caml/alloc.h>
+#include <caml/custom.h>
+#include <caml/mlvalues.h>
+#include <caml/memory.h>
+#include <caml/fail.h>
+#include <caml/misc.h>
+
+static trexio_t* File_val( value file )
+{
+  return *((trexio_t**) Data_abstract_val(file));
+}
+
+
+CAMLprim value caml_open_file(value filename, value mode, value backend)
+{
+  CAMLparam3(filename, mode, backend);
+
+  trexio_exit_code rc = 0;
+  value v = caml_alloc(1, Abstract_tag);
+
+  trexio_t* result = trexio_open (String_val(filename),
+                                  Int_val(mode),
+                                  Int_val(backend),
+                                  &rc);
+
+  *((trexio_t **) Data_abstract_val(v)) = result;
+
+  if (rc == TREXIO_SUCCESS) {
+    CAMLreturn( v );
+  } else  {
+    caml_failwith(trexio_string_of_error(rc));
+  }
+}
+
+
+CAMLprim value caml_close_file(value file)
+{
+  CAMLparam1(file);
+  trexio_exit_code rc = trexio_close( File_val(file) );
+  if (rc == TREXIO_SUCCESS) {
+    CAMLreturn ( Val_unit );
+  } else {
+    caml_failwith(trexio_string_of_error(rc));
+  }
+}
+
+
+CAMLprim value caml_inquire_file(value filename)
+{
+  CAMLparam1 (filename);
+  trexio_exit_code rc = trexio_inquire( String_val (filename) );
+  CAMLreturn(Val_bool(rc == TREXIO_SUCCESS));
+}
+
+
+CAMLprim value caml_set_one_based(value file)
+{
+  CAMLparam1(file);
+  trexio_exit_code rc = trexio_set_one_based( File_val(file) );
+  if (rc == TREXIO_SUCCESS) {
+    CAMLreturn ( Val_unit );
+  } else {
+    caml_failwith(trexio_string_of_error(rc));
+  }
+}
+
+
+CAMLprim value caml_set_state(value file, value state)
+{
+  CAMLparam2(file, state);
+  printf("%d\n", Int_val(state));
+  trexio_exit_code rc = trexio_set_state( File_val(file), (int32_t) Int_val(state) );
+  if (rc == TREXIO_SUCCESS) {
+    CAMLreturn ( Val_unit );
+  } else {
+    caml_failwith(trexio_string_of_error(rc));
+  }
+}
+
+
+CAMLprim value caml_get_state(value file)
+{
+  CAMLparam1(file);
+  int32_t result;
+  trexio_exit_code rc = trexio_get_state( File_val(file), &result );
+  if (rc == TREXIO_SUCCESS) {
+    CAMLreturn ( Val_int(result) );
+  } else {
+    caml_failwith(trexio_string_of_error(rc));
+  }
+}
+
+
+CAMLprim value caml_info(value unit)
+{
+  CAMLparam1(unit);
+  trexio_exit_code rc = trexio_info();
+  if (rc == TREXIO_SUCCESS) {
+    CAMLreturn ( Val_unit );
+  } else {
+    caml_failwith(trexio_string_of_error(rc));
+  }
+}
+
+
+CAMLprim value caml_to_orbital_list(value bitfield)
+{
+  CAMLparam1 ( bitfield );
+  CAMLlocal2 ( result, cons );
+
+  int32_t N_int = Wosize_val(bitfield);
+  bitfield_t* d1 = (bitfield_t*) malloc (N_int * sizeof(bitfield_t));
+  for (int i=0 ; i<N_int ; ++i) {
+      d1[i] = Int64_val(Field(bitfield,i));
+  }
+
+  int32_t* list = (int32_t*) malloc(N_int * sizeof(bitfield_t) * sizeof(int32_t));
+  int32_t occupied_num = 0;
+
+  trexio_exit_code rc = trexio_to_orbital_list (N_int, d1, list, &occupied_num);
+  if (rc != TREXIO_SUCCESS) {
+     caml_failwith(trexio_string_of_error(rc));
+  }
+
+  free(d1);
+
+  result = Val_emptylist;
+  for (int i=occupied_num-1 ; i >= 0 ; --i) {
+    cons = caml_alloc(2, 0);
+    Store_field(cons, 0, Val_int(list[i])); // head
+    Store_field(cons, 1, result); // head
+    result = cons;
+  }
+
+  free(list);
+  CAMLreturn(result);
+}
+
+
+/**** ****/
+
+CAMLprim value caml_read_determinant_list(value file_in, value offset_in, value buffer_size_in)
+{
+  CAMLparam3 ( file_in, offset_in, buffer_size_in );
+  CAMLlocal4 ( result, detup, detdn, det );
+
+  trexio_t* file = File_val(file_in);
+  int64_t offset = Int_val( offset_in );
+  int64_t buffer_size = Int_val( buffer_size_in );
+
+  int32_t int_num = 0;
+  trexio_exit_code rc = trexio_get_int64_num(file, &int_num);
+  if (rc != TREXIO_SUCCESS) {
+     caml_failwith(trexio_string_of_error(rc));
+  }
+
+  int64_t* buffer = (int64_t*) malloc ( buffer_size * int_num * 2 * sizeof(int64_t) );
+
+  rc = trexio_read_determinant_list (file, offset, &buffer_size, buffer);
+  if (rc != TREXIO_SUCCESS) {
+     caml_failwith(trexio_string_of_error(rc));
+  }
+
+  result = caml_alloc(buffer_size, 0);
+  size_t icount = 0;
+  for (size_t i=0 ; i<buffer_size ; ++i) {
+     detup = caml_alloc_initialized_string(int_num*sizeof(int64_t), (char*) &(buffer[icount]));
+     icount += int_num;
+     detdn = caml_alloc_initialized_string(int_num*sizeof(int64_t), (char*) &(buffer[icount]));
+     icount += int_num;
+     det = caml_alloc_tuple(2);
+     Store_field( det, 0, detup );
+     Store_field( det, 1, detdn );
+     Store_field( result, i, det );
+  }
+
+  free(buffer);
+  CAMLreturn(result);
+}
+
+CAMLprim value caml_write_determinant_list(value file_in, value offset_in, value array)
+{
+  CAMLparam3 ( file_in, offset_in, array );
+  CAMLlocal3 ( detup, detdn, det );
+
+  trexio_t* file = File_val(file_in);
+  int64_t offset = Int_val( offset_in );
+  int64_t buffer_size = Wosize_val( array );
+
+  int32_t int_num = 0;
+  trexio_exit_code rc = trexio_get_int64_num(file, &int_num);
+  if (rc != TREXIO_SUCCESS) {
+     caml_failwith(trexio_string_of_error(rc));
+  }
+
+  int64_t* buffer = (int64_t*) malloc ( buffer_size * int_num * 2 * sizeof(int64_t) );
+
+  for (size_t i=0 ; i<buffer_size ; ++i) {
+    det = Field(array, i);
+    detup = Field(det, 0);
+    detdn = Field(det, 1);
+    memcpy(&(buffer[i*int_num*2]), String_val(detup), int_num*sizeof(int64_t));
+    memcpy(&(buffer[i*int_num*2 + int_num]), String_val(detdn), int_num*sizeof(int64_t));
+  }
+
+  rc = trexio_write_determinant_list (file, offset, buffer_size, buffer);
+  if (rc != TREXIO_SUCCESS) {
+     caml_failwith(trexio_string_of_error(rc));
+  }
+
+  free(buffer);
+  CAMLreturn( Val_unit );
+}
+
+CAMLprim value caml_read_determinant_coefficient(value file_in, value offset_in, value buffer_size_in)
+{
+  CAMLparam3 ( file_in, offset_in, buffer_size_in );
+  CAMLlocal1 ( result );
+
+  trexio_t* file = File_val(file_in);
+  int64_t offset = Int_val( offset_in );
+  int64_t buffer_size = Int_val( buffer_size_in );
+
+  double* buffer = (double*) malloc ( buffer_size * sizeof(double) );
+
+  trexio_exit_code rc = trexio_read_determinant_coefficient (file, offset, &buffer_size, buffer);
+  if (rc != TREXIO_SUCCESS) {
+     caml_failwith(trexio_string_of_error(rc));
+  }
+
+  result = caml_alloc(buffer_size * Double_wosize, Double_array_tag);
+  for (size_t i=0 ; i<buffer_size ; ++i) {
+     Store_double_field( result, i, buffer[i]);
+  }
+
+  free(buffer);
+  CAMLreturn(result);
+}
+
+
+CAMLprim value caml_write_determinant_coefficient(value file_in, value offset_in, value array)
+{
+  CAMLparam3 ( file_in, offset_in, array );
+
+  trexio_t* file = File_val(file_in);
+  int64_t offset = Int_val( offset_in );
+  int64_t buffer_size = Wosize_val( array );
+
+  double* buffer = (double*) malloc ( buffer_size * sizeof(double) );
+
+  for (size_t i=0 ; i<buffer_size ; ++i) {
+    buffer[i] = Double_field(array, i);
+  }
+
+  trexio_exit_code rc = trexio_write_determinant_coefficient (file, offset, buffer_size, buffer);
+  if (rc != TREXIO_SUCCESS) {
+     caml_failwith(trexio_string_of_error(rc));
+  }
+
+  free(buffer);
+  CAMLreturn( Val_unit );
+}
+
+

python/MANIFEST.in

@@ -1,8 +1,9 @@
-include src/*.c 
+include src/*.c
-include src/trexio*.h 
+include src/trexio*.h
-include examples/notebooks/* 
+include examples/notebooks/*
-include examples/README.md 
+include examples/README.md
 include requirements.txt tools/set_NUMPY_INCLUDEDIR.sh
+include test/benzene_data.py
 
 exclude examples/LICENSE
 exclude examples/requirements.txt

python/README.md

@@ -12,8 +12,7 @@ can be used to convert data from one input/output file format into another.
 ## Requirements
 
 - python3 	(>= 3.6)
-- numpy		(>= 1.17.3)
+- numpy		  (>= 1.17.3)
-
 
 ## Installation from PyPI
 
@@ -31,10 +30,11 @@ For more details, see the corresponding part of the [Python documentation](https
 
 ## Additional requirements (for installation from source)
 
-- C compiler 	(gcc/icc/clang)
+- C compiler 	  (gcc/icc/clang)
 - HDF5 library	(>= 1.8)
 - pkgconfig     (Python package)
 - build         (Python package)
+- pytest        (Python package)
 
 ## Installation from source
 
@@ -44,10 +44,10 @@ For more details, see the corresponding part of the [Python documentation](https
 4. `pip install -r requirements.txt` (this installs all required python dependencies)
 5. Export custom environment variables needed for the installation following the procedure below and replacing `/path/to/hdf5/` with your paths.
 The following two steps can be skipped if HDF5 is properly configured for `pkg-config` (i.e. if executing `pkg-config --libs hdf5` returns a list of options).
-   1. `export H5_CFLAGS=-I/path/to/hdf5/include`
+   - `export H5_CFLAGS=-I/path/to/hdf5/include`
-   2. `export H5_LDFLAGS=-L/path/to/hdf5/lib`
+   - `export H5_LDFLAGS=-L/path/to/hdf5/lib`
 6. `pip install .` (this installs `trexio` in your environment)
-7. `cd test && python test_api.py` (this executes several tests that verify the installation)
+7. `cd test && python -m pytest -v test_api.py` (this executes several tests that verify the installation)
 
 You are ready to go!
 

python/build_manylinux_wheels.sh

@@ -82,11 +82,14 @@ function build_wheel_for_py()
    # install the produced manylinux wheel in the virtual environment
    python3 -m pip install wheelhouse/trexio-${TR_VERSION}-${CPYTHON}-manylinux*.whl
 
+   # install pytest for testing
+   pip install pytest
    # run test script
-   cd test && python3 test_api.py && cd ..
+   pytest -v test/test_api.py
 
    # cleaning
-   rm -rf -- dist/ build/ trexio.egg-info/
+   rm -rf -- dist/ build/ trexio.egg-info/ 
+   rm -- test_file_py.h5 unsafe_test_file_py.h5
 
    # deactivate the current environment
    deactivate

python/install_pytrexio.sh

@@ -28,6 +28,7 @@ fi
 # Install/upgrade packages required for the installation
 python3 -m pip install --upgrade setuptools build pip
 python3 -m pip install -r requirements.txt
+python3 -m pip install pytest
 
 # export NUMPY_INCLUDEDIR environment variable needed for the proper setup
 #source tools/set_NUMPY_INCLUDEDIR.sh

python/pytrexio/_version.py

@@ -1 +1 @@
-__version__ = "1.2.0"
+__version__ = "1.3.0"

python/setup.py

@@ -9,7 +9,7 @@ from setuptools import setup, Extension
 
 def parse_setuppy_commands():
     """Check the commands and respond appropriately.
-    At the moment it is adapted to ignore checks for numpy, plgconfig, HDF5 flags
+    At the moment it is adapted to ignore checks for numpy, pkgconfig, HDF5 flags
     when building the distribution tarball with sdist option.
     """
     args = sys.argv[1:]
@@ -93,7 +93,12 @@ pytrexio_module = Extension('pytrexio._pytrexio',
                             sources = [os.path.join(srcpath, code) for code in c_files],
                             include_dirs = [h5_cflags, srcpath, numpy_includedir],
                             libraries = ['hdf5', 'hdf5_hl'],
-                            extra_compile_args = ['-Wno-discarded-qualifiers'],
+                            extra_compile_args = [
+                                '-std=c99',
+                                '-Wno-discarded-qualifiers',
+                                '-Wno-unused-variable',
+                                '-Wno-unused-but-set-variable'
+                                ],
                             extra_link_args = [h5_ldflags]
                             )
 

python/test/benzene_data.py

@@ -0,0 +1,49 @@
+
+# for the nucleus group
+nucleus_num    = 12
+
+point_group    = 'D6h'
+
+nucleus_label  = ['C', 'C', 'C', 'C', 'C', 'C', 'H', 'H', 'H', 'H', 'H', 'H']
+
+nucleus_charge = [6., 6., 6., 6., 6., 6., 1., 1., 1., 1., 1., 1.]
+
+nucleus_coord  = [
+[ 0.00000000 ,  1.39250319 ,  0.00000000 ],
+[-1.20594314 ,  0.69625160 ,  0.00000000 ],
+[-1.20594314 , -0.69625160 ,  0.00000000 ],
+[ 0.00000000 , -1.39250319 ,  0.00000000 ],
+[ 1.20594314 , -0.69625160 ,  0.00000000 ],
+[ 1.20594314 ,  0.69625160 ,  0.00000000 ],
+[-2.14171677 ,  1.23652075 ,  0.00000000 ],
+[-2.14171677 , -1.23652075 ,  0.00000000 ],
+[ 0.00000000 , -2.47304151 ,  0.00000000 ],
+[ 2.14171677 , -1.23652075 ,  0.00000000 ],
+[ 2.14171677 ,  1.23652075 ,  0.00000000 ],
+[ 0.00000000 ,  2.47304151 ,  0.00000000 ],
+]
+
+# for the basis_nucleus_index
+basis_shell_num = 24
+nucleus_index   = [i for i in range(basis_shell_num)]
+
+# for sparse AO_INT_2E
+ao_num = 600
+# prepare the sparse data representation
+num_integrals = 100
+indices       = [i for i in range(num_integrals*4)]
+values        = [(3.14 + float(i)) for i in range(num_integrals)]
+
+# for determinants
+mo_num    = 150
+int64_num = int((mo_num - 1)/64 + 1)
+# prepate the CI data
+det_num   = 2000
+dets      = [i for i in range(det_num * int64_num * 2)]
+coeffs    = [float(i/det_num)   for i in range(det_num)]
+coeffs_s2 = [float(i*2/det_num) for i in range(det_num)]
+
+det_test  = [1, 2, 3, 2, 1, 3]
+
+orb_up_test = [0, 65, 128, 129]
+orb_dn_test = [1, 64, 128, 129]

python/test/test_api.py

@@ -1,325 +1,337 @@
 #!/usr/bin/env python3
 
-import os
-import shutil
 import numpy as np
-
+import pytest
 import trexio
+from benzene_data import *
 
-#=========================================================#
-#======== SETUP THE BACK END AND OUTPUT FILE NAME ========#
-#=========================================================#
-
-# 0: TREXIO_HDF5 ; 1: TREXIO_TEXT
-TEST_TREXIO_BACKEND = 0
-OUTPUT_FILENAME_TEXT = 'test_py_swig.dir'
-OUTPUT_FILENAME_HDF5 = 'test_py_swig.h5'
-
-
-# define TREXIO file name
-if TEST_TREXIO_BACKEND == trexio.TREXIO_HDF5:
-    output_filename = OUTPUT_FILENAME_HDF5
-elif TEST_TREXIO_BACKEND == trexio.TREXIO_TEXT:
-    output_filename = OUTPUT_FILENAME_TEXT
-else:
-    raise ValueError ('Specify one of the supported back ends as TEST_TREXIO_BACKEND')
-
-
-# remove TREXIO file if exists in the current directory
-try:
-    if TEST_TREXIO_BACKEND == trexio.TREXIO_HDF5:
-        os.remove(output_filename)
-    elif TEST_TREXIO_BACKEND == trexio.TREXIO_TEXT:
-        shutil.rmtree(output_filename)
-except:
-    print('Nothing to remove.')
 
-#=========================================================#
+FILENAME = 'test_file_py.h5'
-#============ WRITE THE DATA IN THE TEST FILE ============#
+BACK_END = trexio.TREXIO_HDF5
-#=========================================================#
 
-trexio.info()
 
+def clean():
+    """Remove test files."""
+    import os
 
-# test with ... as ... block
+    try:
-with trexio.File(output_filename, mode='w', back_end=TEST_TREXIO_BACKEND) as tfile:
+        os.remove(FILENAME)
-    trexio.write_metadata_description(tfile, "Test file produced by the Python API")
+        os.remove('unsafe_' + FILENAME)
-    assert trexio.has_metadata_description(tfile)
+    except FileNotFoundError:
-    assert tfile.isOpen
+        pass
-
-# the file handle can remain existing but the file itself is closed upon exit from the `with` block
-assert not tfile.isOpen
-
-
-# create TREXIO file and open it for writing
-test_file = trexio.File(output_filename, mode='w', back_end=TEST_TREXIO_BACKEND)
-assert test_file.exists
-
-# Print docstring of the trexio.open function
-#print(trexio.open.__doc__)
-
-nucleus_num = 12
-
-try:
-    trexio.write_nucleus_num(test_file, -100)
-except trexio.Error:
-    print("Raise error for an attempt to write negative nucleus_num: checked.")
-
-# write nucleus_num in the file
-try:
-    trexio.write_nucleus_num(test_file, nucleus_num)
-except:
-    raise
-
-try:
-    trexio.write_nucleus_num(test_file, nucleus_num*2)
-except trexio.Error:
-    print("Raise error for an attempt to overwrite nucleus_num: checked.")
 
-# initialize charge arrays as a list and convert it to numpy array
+
-charges = [6., 6., 6., 6., 6., 6., 1., 1., 1., 1., 1., 1.]
+def test_info():
-#charges_np = np.array(charges, dtype=np.float32)
+    """Print the output of the trexio.info function."""
-charges_np = np.array(charges, dtype=np.int32)
+    trexio.info()
-
+
-# function call below works with both lists and numpy arrays, dimension needed for memory-safety is derived
+
-# from the size of the list/array by SWIG using typemaps from numpy.i
+def test_void():
-trexio.write_nucleus_charge(test_file, charges_np)
+    """Check raise of an error upon I/O on non-existing file."""
-
+    with pytest.raises(trexio.Error):
-basis_shell_num = 24
+        _ = trexio.File('void.file', 'r', BACK_END)
-# initialize arrays of nuclear indices as a list and convert it to numpy array
+
-indices = [i for i in range(basis_shell_num)]
+
-# type cast is important here because by default numpy transforms a list of integers into int64 array
+def test_orbital_list():
-indices_np = np.array(indices, dtype=np.int64)
+    """Convert one determinant into a list of orbitals."""
-
+    orb_list_up, orb_list_dn = trexio.to_orbital_list_up_dn(int64_num, det_test)
-# first write basis_shell_num because it is needed to check dimensions of basis_nucleus_index in TREXIO >= 2.0.0
+    assert orb_list_up[0] == 0
-trexio.write_basis_shell_num(test_file, basis_shell_num)
+    assert orb_list_dn[0] == 1
-
+
-# function call below works with both lists and numpy arrays, dimension needed for memory-safety is derived
+
-# from the size of the list/array by SWIG using typemacs from numpy.i
+def test_bitfield_list():
-trexio.write_basis_nucleus_index(test_file, indices_np)
+    """Convert lists of occupied up- and down-spin orbitals into determinants."""
-
+    # convert det_test list into a numpy array for .all() assertion to work
-# initialize a list of nuclear coordinates
+    det_test_np = np.array(det_test, dtype=np.int64)
-coords = [
+
- [ 0.00000000 ,  1.39250319 ,  0.00000000 ],
+    det_list_up = trexio.to_bitfield_list(int64_num, orb_up_test)
- [-1.20594314 ,  0.69625160 ,  0.00000000 ],
+    assert (det_list_up == det_test_np[:int64_num]).all()
- [-1.20594314 , -0.69625160 ,  0.00000000 ],
+    det_list_dn = trexio.to_bitfield_list(int64_num, orb_dn_test)
- [ 0.00000000 , -1.39250319 ,  0.00000000 ],
+    assert (det_list_dn == det_test_np[int64_num:]).all()
- [ 1.20594314 , -0.69625160 ,  0.00000000 ],
+
- [ 1.20594314 ,  0.69625160 ,  0.00000000 ],
+
- [-2.14171677 ,  1.23652075 ,  0.00000000 ],
+class TestIO:
- [-2.14171677 , -1.23652075 ,  0.00000000 ],
+    """Unit tests for writing/reading different blocks of the TREXIO file."""
- [ 0.00000000 , -2.47304151 ,  0.00000000 ],
+
- [ 2.14171677 , -1.23652075 ,  0.00000000 ],
+    filename  = FILENAME
- [ 2.14171677 ,  1.23652075 ,  0.00000000 ],
+    back_end  = BACK_END
- [ 0.00000000 ,  2.47304151 ,  0.00000000 ],
+    mode      = 'w'
-  ]
+    test_file = None
-
+
-# write coordinates in the file
+    clean()
-trexio.write_nucleus_coord(test_file, coords)
+
-
+
-
+    def __del__(self):
-# write mo_num (needed later to write sparse mo_2e_int_eri integrals)
+        if self.test_file:
-trexio.write_mo_num(test_file, 600)
+            if self.test_file.isOpen:
-
+                self.test_file.close()
-# write sparse data in the file
+
-num_integrals = 100
+
-indices = [i for i in range(num_integrals*4)]
+    def open(self, filename=None, mode=None, back_end=None):
-values  = [(3.14 + float(i)) for i in range(num_integrals)]
+        """Create a TREXIO file and open it for writing."""
-
+        if not filename:
-trexio.write_mo_2e_int_eri(test_file, 0, num_integrals, indices, values)
+            filename = self.filename
-
+        else:
-
+            self.filename = filename
-# write nucleus_point_group in the file
+        if not mode:
-point_group = 'B3U'
+            mode = self.mode
-
+        else:
-trexio.write_nucleus_point_group(test_file, point_group)
+            self.mode = mode
-
+        if not back_end:
-
+            back_end = self.back_end
-# write nucleus_label in the file
+        else:
-labels = [
+            self.back_end = back_end
-        'C',
+
-        'C',
+        self.test_file = trexio.File(filename, mode, back_end)
-        'C',
+        assert self.test_file.exists
-        'C',
+
-        'C',
+
-        'C',
+    def test_close(self):
-        'H',
+        """Close the file."""
-        'H',
+        self.open()
-        'H',
+        if self.test_file.isOpen:
-        'H',
+            self.test_file.close()
-        'H',
+        assert not self.test_file.isOpen
-        'H']
+
-
+
-trexio.write_nucleus_label(test_file,labels)
+    def test_errors(self):
-
+        """Test some exceptions based on trexio.Error class."""
-# close TREXIO file
+        self.open(filename='unsafe_' + self.filename, mode='w', back_end=self.back_end)
-# this call is no longer needed as we introduced TREXIO_File class which has a desctructor that closes the file
+        # try to write a negative number (should raise an error)
-#trexio.close(test_file)
+        with pytest.raises(trexio.Error):
-# without calling destructor on test_file the TREXIO_FILE is not getting created and the data is not written when using TEXT back end.
+            trexio.write_nucleus_num(self.test_file, -100)
-# This, the user still has to explicitly call destructor on test_file object instead of the trexio.close function.
+
-# This is only an issue when the data is getting written and read in the same session (e.g. in Jupyter notebook)
+        trexio.write_nucleus_num(self.test_file, nucleus_num)
-del test_file
+
-
+        # try to overwrite a number (should raise an error)
-
+        with pytest.raises(trexio.Error):
-#==========================================================#
+            trexio.write_nucleus_num(self.test_file, nucleus_num * 2)
-#========== DELETE THE GROUP FROM THE TEST FILE ===========#
+
-#==========================================================#
+
-
+    def test_num(self):
-unsafe_file = trexio.File(output_filename, 'u', TEST_TREXIO_BACKEND)
+        """Write a number."""
-
+        self.open()
-# overwrite existing data (only allowed in 'u' - unsafe mode)
+        trexio.write_nucleus_num(self.test_file, nucleus_num)
-trexio.write_nucleus_num(unsafe_file, nucleus_num)
+        assert trexio.has_nucleus_num(self.test_file)
-trexio.write_nucleus_charge(unsafe_file, charges_np)
+
-trexio.write_nucleus_coord(unsafe_file, coords)
+
-trexio.write_nucleus_label(unsafe_file,labels)
+    def test_str(self):
-trexio.write_nucleus_point_group(unsafe_file, point_group)
+        """Write a string."""
-
+        self.open()
-print("Overwriting the data in UNSAFE mode: checked")
+        trexio.write_nucleus_point_group(self.test_file, point_group)
-
+        assert trexio.has_nucleus_point_group(self.test_file)
-# delete existing group (only allowed in 'u' - unsafe mode)
+
-trexio.delete_nucleus(unsafe_file)
+
-
+    def test_array_str(self):
-assert not trexio.has_nucleus_num(unsafe_file)
+        """Write an array of strings."""
-assert not trexio.has_nucleus_charge(unsafe_file)
+        self.open()
-assert not trexio.has_nucleus_coord(unsafe_file)
+        if not trexio.has_nucleus_num(self.test_file):
-assert not trexio.has_nucleus_label(unsafe_file)
+            self.test_num()
-assert not trexio.has_nucleus_point_group(unsafe_file)
+        trexio.write_nucleus_label(self.test_file, nucleus_label)
-
+        assert trexio.has_nucleus_label(self.test_file)
-print("Deleting nucleus group in UNSAFE mode: checked")
+
-
+
-# restore the deleted data
+    def test_array_1D(self):
-trexio.write_nucleus_num(unsafe_file, nucleus_num)
+        """Write array of charges."""
-trexio.write_nucleus_charge(unsafe_file, charges_np)
+        self.open()
-trexio.write_nucleus_coord(unsafe_file, coords)
+        if not trexio.has_nucleus_num(self.test_file):
-trexio.write_nucleus_label(unsafe_file,labels)
+            self.test_num()
-trexio.write_nucleus_point_group(unsafe_file, point_group)
+        trexio.write_nucleus_charge(self.test_file, nucleus_charge)
-
+        assert trexio.has_nucleus_charge(self.test_file)
-del unsafe_file
+
-
+
-#==========================================================#
+    def test_array_2D(self):
-#============ READ THE DATA FROM THE TEST FILE ============#
+        """Write array of coordinates."""
-#==========================================================#
+        self.open()
-
+        if not trexio.has_nucleus_num(self.test_file):
-# open previously created TREXIO file, now in 'read' mode
+            self.test_num()
-test_file2 = trexio.File(output_filename, 'r', trexio.TREXIO_AUTO)
+        trexio.write_nucleus_coord(self.test_file, nucleus_coord)
-assert test_file2.exists
+        assert trexio.has_nucleus_coord(self.test_file)
-
+
-# check for existence of some of the previously written variables
+
-assert trexio.has_nucleus_num(test_file2)
+    def test_indices(self):
-assert trexio.has_nucleus_charge(test_file2)
+        """Write array of indices."""
-assert trexio.has_nucleus_coord(test_file2)
+        self.open()
-assert trexio.has_nucleus_label(test_file2)
+        # type cast is important here because by default numpy transforms a list of integers into int64 array
-assert trexio.has_nucleus_point_group(test_file2)
+        indices_np = np.array(nucleus_index, dtype=np.int64)
-assert trexio.has_mo_2e_int_eri(test_file2)
+        # first write basis_shell_num because it is needed to check dimensions of basis_nucleus_index
-
+        trexio.write_basis_shell_num(self.test_file, basis_shell_num)
-# read nucleus_num from file
+        # now write the indices
-rnum = trexio.read_nucleus_num(test_file2)
+        trexio.write_basis_nucleus_index(self.test_file, indices_np)
-assert rnum==nucleus_num
+        assert trexio.has_basis_nucleus_index(self.test_file)
-
+
-# safe call to read_nucleus_charge array of float values
+
-rcharges_np = trexio.read_nucleus_charge(test_file2, dim=nucleus_num)
+    def test_sparse(self):
-assert rcharges_np.dtype is np.dtype(np.float64)
+        """Write a sparse array."""
-np.testing.assert_array_almost_equal(rcharges_np, charges_np, decimal=8)
+        self.open()
-
+        # write ao_num (needed later to write sparse ao_2e_int_eri integrals)
-# unsafe call to read_safe should fail with error message corresponding to TREXIO_UNSAFE_ARRAY_DIM
+        trexio.write_ao_num(self.test_file, ao_num)
-try:
+        # one complete write (no chunking)
-    rcharges_fail = trexio.read_nucleus_charge(test_file2, dim=nucleus_num*5)
+        offset = 0
-except trexio.Error:
+        trexio.write_ao_2e_int_eri(self.test_file, offset, num_integrals, indices, values)
-    print("Unsafe call to safe API: checked")
+        assert trexio.has_ao_2e_int_eri(self.test_file)
-
+
-# safe call to read array of int values (nuclear indices)
+
-rindices_np_16 = trexio.read_basis_nucleus_index(test_file2, dim=basis_shell_num, dtype=np.int16)
+    def test_determinant(self):
-assert rindices_np_16.dtype is np.dtype(np.int16)
+        """Write CI determinants and coefficients."""
-for i in range(basis_shell_num):
+        self.open()
-    assert rindices_np_16[i]==indices_np[i]
+        # write mo_num (needed later to write determinants)
-
+        trexio.write_mo_num(self.test_file, mo_num)
-rindices_np_32 = trexio.read_basis_nucleus_index(test_file2, dim=basis_shell_num, dtype=np.int32)
+        # get the number of bit-strings per spin component
-assert rindices_np_32.dtype is np.dtype(np.int32)
+        int_num = trexio.get_int64_num(self.test_file)
-for i in range(basis_shell_num):
+        assert int_num == int64_num
-    assert rindices_np_32[i]==indices_np[i]
+        # write the data for the ground state
-
+        offset = 0
-rindices_np_64 = trexio.read_basis_nucleus_index(test_file2)
+        trexio.write_state_id(self.test_file, 0)
-assert rindices_np_64.dtype is np.dtype(np.int64)
+        trexio.write_determinant_list(self.test_file, offset, det_num, dets)
-assert rindices_np_64.size==basis_shell_num
+        assert trexio.has_determinant_list(self.test_file)
-for i in range(basis_shell_num):
+        trexio.write_determinant_coefficient(self.test_file, offset, det_num, coeffs)
-    assert rindices_np_64[i]==indices_np[i]
+        assert trexio.has_determinant_coefficient(self.test_file)
-
+        # manually check the consistency between coefficient_size and number of determinants
-# read nuclear coordinates without providing optional argument dim
+        assert trexio.read_determinant_coefficient_size(self.test_file) == trexio.read_determinant_num(self.test_file)
-rcoords_np = trexio.read_nucleus_coord(test_file2)
+
-
+
-assert rcoords_np.size==nucleus_num*3
+    def test_delete_group(self):
-np.testing.assert_array_almost_equal(rcoords_np, np.array(coords).reshape(nucleus_num,3), decimal=8)
+        """Delete a group."""
-
+        self.open(filename='unsafe_' + self.filename, mode='u', back_end=self.back_end)
-# set doReshape to False to get a flat 1D array (e.g. when reading matrices like nuclear coordinates)
+
-#rcoords_reshaped_2 = trexio.read_nucleus_coord(test_file2, doReshape=False)
+        self.test_num()
-
+        self.test_array_1D()
-# read number of integrals already present in the file
+        self.test_array_2D()
-assert trexio.has_mo_2e_int_eri(test_file2)
+
-assert trexio.read_mo_2e_int_eri_size(test_file2)==num_integrals
+        assert trexio.has_nucleus(self.test_file)
-
+
-# read sparse arrays on mo_2e_int_eri integrals
+        trexio.delete_nucleus(self.test_file)
-buf_size = 60
+
-offset_file = 0
+        assert not trexio.has_nucleus_num(self.test_file)
-# read full buf_size (i.e. the one that does not reach EOF)
+        assert not trexio.has_nucleus_charge(self.test_file)
-indices_sparse_np, value_sparse_np, read_buf_size, eof = trexio.read_mo_2e_int_eri(test_file2, offset_file, buf_size)
+        assert not trexio.has_nucleus_coord(self.test_file)
-print(f'First complete sparse read size: {read_buf_size}')
+        assert not trexio.has_nucleus(self.test_file)
-#print(indices_sparse_np)
+
-assert not eof
+
-assert read_buf_size==buf_size
+    def test_has_group(self):
-assert indices_sparse_np[0][0]==0
+        """Check existense of a group."""
-assert indices_sparse_np[read_buf_size-1][3]==read_buf_size*4-1
+        self.open()
-offset_file += buf_size
+        assert trexio.has_nucleus(self.test_file)
-
+        assert not trexio.has_rdm(self.test_file)
-# read incomplete buf_size (i.e. the one that does reach EOF)
+
-indices_sparse_np, value_sparse_np, read_buf_size, eof2 = trexio.read_mo_2e_int_eri(test_file2, offset_file, buf_size)
+
-print(f'Second incomplete sparse read size: {read_buf_size}')
+    def test_context_manager(self):
-#print(indices_sparse_np)
+        """Test the with ... as ... context handling."""
-assert eof2
+        with trexio.File(filename=self.filename, mode='u', back_end=self.back_end) as tfile:
-assert read_buf_size==(num_integrals - buf_size)
+            trexio.write_metadata_description(tfile, 'Test file produced by the Python API')
-assert indices_sparse_np[0][0]==offset_file*4
+            assert trexio.has_metadata_description(tfile)
-assert indices_sparse_np[read_buf_size-1][3]==(offset_file+read_buf_size)*4-1
+            assert tfile.isOpen
-
+        # the file handle can remain existing but the file itself is closed upon exit from the `with` block
-
+        assert not tfile.isOpen
-# read array of nuclear labels
+
-rlabels_2d = trexio.read_nucleus_label(test_file2, dim=nucleus_num)
+
-print(rlabels_2d)
+    def test_read_num(self):
-for i in range(nucleus_num):
+        """Read a number."""
-    assert rlabels_2d[i]==labels[i]
+        self.open(mode='r')
-
+        num_r = trexio.read_nucleus_num(self.test_file)
-# read a string corresponding to nuclear point group
+        assert num_r == nucleus_num
-rpoint_group = trexio.read_nucleus_point_group(test_file2)
+
-assert rpoint_group==point_group
+
-
+    def test_read_array_1D(self):
-# another way to read only if the variable exists
+        """Read an array."""
-if trexio.has_ao_num(test_file2):
+        self.open(mode='r')
-    rao_num = trexio.read_ao_num(test_file2)
+        charges_np_r = trexio.read_nucleus_charge(self.test_file)
-else:
+        assert charges_np_r.dtype is np.dtype(np.float64)
-    print("Pass on reading the non-existing variable ao_num: checked")
+        assert charges_np_r.size == nucleus_num
-
+        np.testing.assert_array_almost_equal(charges_np_r, np.array(nucleus_charge), decimal=8)
-# close TREXIO file
+
-#trexio.close(test_file2)
+
-
+    def test_read_array_2D(self):
-# cleaning (remove the TREXIO file)
+        """Read an array."""
-try:
+        self.open(mode='r')
-   if TEST_TREXIO_BACKEND == trexio.TREXIO_HDF5:
+        # read nuclear coordinates without providing optional argument dim
-       os.remove(output_filename)
+        coords_np = trexio.read_nucleus_coord(self.test_file)
-   elif TEST_TREXIO_BACKEND == trexio.TREXIO_TEXT:
+        assert coords_np.dtype is np.dtype(np.float64)
-       shutil.rmtree(output_filename)
+        assert coords_np.size == nucleus_num * 3
-except:
+        np.testing.assert_array_almost_equal(coords_np, np.array(nucleus_coord).reshape(nucleus_num,3), decimal=8)
-    print(f'No output file {output_filename} has been produced')
+
-
+
-#==========================================================#
+    def test_read_errors(self):
-
+        """Test some reading errors."""
-#==========================================================#
+        self.open(mode='r')
-#======= OPEN NON-EXISTING FILE TO TEST TREXIO.OPEN =======#
+        # unsafe call to read_safe should fail with error message corresponding to TREXIO_UNSAFE_ARRAY_DIM
-#==========================================================#
+        with pytest.raises(trexio.Error):
-
+            _ = trexio.read_nucleus_charge(self.test_file, dim=nucleus_num/2)
-try:
+
-    void_file = trexio.File('non_existing.file', 'r', TEST_TREXIO_BACKEND)
+
-except trexio.Error as e:
+    def test_read_integers(self):
-    if e.error == trexio.TREXIO_OPEN_ERROR:
+        """Read some integer arrays."""
-        print("Opening non-existing file returns TREXIO_OPEN_ERROR: checked")
+        self.open(mode='r')
-    else:
+
-        raise ValueError("[DEV]: error handling of trexio_open function has changed; check the consistency")
+        indices_np_16 = trexio.read_basis_nucleus_index(self.test_file, dtype=np.int16)
-
+        assert indices_np_16.dtype is np.dtype(np.int16)
-#==========================================================#
+        assert (indices_np_16 == np.array(nucleus_index)).all()
+
+        indices_np_32 = trexio.read_basis_nucleus_index(self.test_file, dtype=np.int32)
+        assert indices_np_32.dtype is np.dtype(np.int32)
+        assert (indices_np_32 == np.array(nucleus_index)).all()
+
+        indices_np_64 = trexio.read_basis_nucleus_index(self.test_file)
+        assert indices_np_64.dtype is np.dtype(np.int64)
+        assert indices_np_64.size == basis_shell_num
+        assert (indices_np_64 == np.array(nucleus_index)).all()
+
+
+    def test_sparse_read(self):
+        """Read a sparse array."""
+        self.open(mode='r')
+        # read sparse arrays on ao_2e_int_eri integrals
+        buf_size    = 60
+        offset_file = 0
+        # read full buf_size (i.e. the one that does not reach EOF)
+        indices_sparse_np, value_sparse_np, read_buf_size, eof = trexio.read_ao_2e_int_eri(self.test_file, offset_file, buf_size)
+        #print(f'First complete sparse read size: {read_buf_size}')
+        assert not eof
+        assert read_buf_size == buf_size
+        assert indices_sparse_np[0][0] == 0
+        assert indices_sparse_np[read_buf_size-1][3] == read_buf_size * 4 - 1
+
+        offset_file += buf_size
+        # read incomplete buf_size (i.e. the one that does reach EOF)
+        indices_sparse_np, value_sparse_np, read_buf_size, eof = trexio.read_ao_2e_int_eri(self.test_file, offset_file, buf_size)
+        #print(f'Second incomplete sparse read size: {read_buf_size}')
+        assert eof
+        assert read_buf_size == (num_integrals - buf_size)
+        assert indices_sparse_np[0][0] == offset_file * 4
+        assert indices_sparse_np[read_buf_size-1][3] == (offset_file + read_buf_size) * 4 - 1
+
+
+    def test_determinant_read(self):
+        """Read the CI determinants."""
+        self.open(mode='r')
+        # read determinants (list of ints and float coefficients)
+        buf_size    = 100
+        offset_file = 0
+        # read full buf_size (i.e. the one that does not reach EOF)
+        dets_np, read_buf_size, eof = trexio.read_determinant_list(self.test_file, offset_file, buf_size)
+        #print(f'First complete read of determinant list: {read_buf_size}')
+        assert not eof
+        assert read_buf_size == buf_size
+        assert dets_np[0][0] == 0
+        assert dets_np[read_buf_size-1][int64_num*2-1] == read_buf_size * int64_num * 2- 1
+
+        coefficients_np, read_buf_size, eof = trexio.read_determinant_coefficient(self.test_file, offset_file, buf_size)
+        #print(f'First complete read of determinant coefficients: {read_buf_size}')
+        assert not eof
+        assert read_buf_size == buf_size
+
+
+    def test_array_str_read(self):
+        """Read an array of strings."""
+        self.open(mode='r')
+        labels_r = trexio.read_nucleus_label(self.test_file)
+        assert len(labels_r) == nucleus_num
+        assert labels_r == nucleus_label
+
+
+    def test_str_read(self):
+        """Read a string."""
+        self.open(mode='r')
+        point_group_r = trexio.read_nucleus_point_group(self.test_file)
+        assert point_group_r == point_group

src/pytrexio.i

@@ -36,6 +36,10 @@
 /* Return num variables as part of the output tuple */
 %apply int *OUTPUT { int32_t* const num};
 %apply int *OUTPUT { int64_t* const num};
+%apply int *OUTPUT { int32_t* const num_up};
+%apply int *OUTPUT { int32_t* const num_dn};
+%apply int *OUTPUT { int64_t* const num_up};
+%apply int *OUTPUT { int64_t* const num_dn};
 %apply float *OUTPUT { float* const num};
 %apply float *OUTPUT { double* const num};
 /* Return TREXIO exit code from trexio_open as part of the output tuple */
@@ -75,6 +79,7 @@ import_array();
 %numpy_typemaps(float, NPY_FLOAT, int64_t)
 %numpy_typemaps(int32_t, NPY_INT32, int64_t)
 %numpy_typemaps(int64_t, NPY_INT64, int64_t)
+%numpy_typemaps(bitfield_t, NPY_INT64, int64_t)
 /* Enable write|read_safe functions to convert numpy arrays from/to double arrays */
 %apply (double* ARGOUT_ARRAY1, int64_t DIM1) {(double* const dset_out, const int64_t dim_out)};
 %apply (double* IN_ARRAY1, int64_t DIM1) {(const double* dset_in, const int64_t dim_in)};
@@ -93,6 +98,15 @@ import_array();
 
 %apply (double* ARGOUT_ARRAY1, int64_t DIM1) {(double* const value_sparse_read, const int64_t size_value_read)};
 %apply (int32_t* ARGOUT_ARRAY1, int64_t DIM1) {(int32_t* const index_sparse_read, const int64_t size_index_read)};
+/* Enable write|read_safe functions to convert numpy arrays from orbital list arrays */
+%apply (int32_t* ARGOUT_ARRAY1, int64_t DIM1) {(int32_t* const dset_up_out, const int64_t dim_up_out)};
+%apply (int32_t* ARGOUT_ARRAY1, int64_t DIM1) {(int32_t* const dset_dn_out, const int64_t dim_dn_out)};
+%apply (int64_t* ARGOUT_ARRAY1, int64_t DIM1) {(int64_t* const dset_up_out, const int64_t dim_up_out)};
+%apply (int64_t* ARGOUT_ARRAY1, int64_t DIM1) {(int64_t* const dset_dn_out, const int64_t dim_dn_out)};
+%apply (bitfield_t* IN_ARRAY1, int64_t DIM1) {(const bitfield_t* dset_in, const int64_t dim_in)};
+%apply (int32_t* IN_ARRAY1, int32_t DIM1) {(const int32_t* orb_list, const int32_t occupied_num)};
+/* For some reasons SWIG does not apply the proper bitfield_t typemap, so one has to manually specify int64_t* ARGOUT_ARRAY1 below */
+%apply (int64_t* ARGOUT_ARRAY1, int32_t DIM1) {(bitfield_t* const bit_list, const int32_t N_int)};
 
 /* This tells SWIG to treat char ** dset_in pattern as a special case
    Enables access to trexio_[...]_write_dset_str set of functions directly, i.e.

src/templates_front/build.sh

@@ -38,9 +38,18 @@ echo "" >> trexio_f.f90
 # c front end
 cat populated/pop_*.c >> trexio.c
 cat populated/pop_*.h >> trexio.h
+# add determinant part
+cat hrw_determinant_front.h >> trexio.h
+cat *_determinant_front.c >> trexio.c
+
+# private API header file
+cat populated/private_pop_front.h >> trexio_private.h
+echo "#endif" >> trexio_private.h
 
 # fortran front end
 cat populated/pop_*.f90  >> trexio_f.f90
+# add determinant part
+cat *_determinant_front_fortran.f90 >> trexio_f.f90
 # add helper functions
 cat helper_fortran.f90 >> trexio_f.f90
 cat populated/pop_*.fh_90 >> trexio_f.f90
@@ -48,6 +57,7 @@ cat populated/pop_*.fh_90 >> trexio_f.f90
 # python front end
 cat basic_python.py >> trexio.py
 cat populated/pop_*.py >> trexio.py
+cat *_determinant_front.py >> trexio.py
 
 # suffixes
 cat suffix_s_front.h >> trexio_s.h

src/templates_hdf5/build.sh

@@ -14,5 +14,8 @@ cat populated/pop_delete_group_hdf5.c >> trexio_hdf5.c
 cat populated/pop_hrw_*.h >> trexio_hdf5.h
 cat populated/pop_delete_group_hdf5.h >> trexio_hdf5.h
 
+cat hrw_determinant_hdf5.h >> trexio_hdf5.h
+cat *_determinant_hdf5.c >> trexio_hdf5.c
+
 cat helpers_hdf5.c  >> trexio_hdf5.c
 cat suffix_hdf5.h   >> trexio_hdf5.h

src/templates_hdf5/templator_hdf5.org

@@ -60,6 +60,11 @@
 
 * Template for HDF5 structures
 
+   Polymorphism of the ~trexio_t~ type is handled by ensuring that the
+   corresponding types for all back ends can be safely casted to
+ ~trexio_t~. This is done by making the back-end structs start with
+ ~trexio_t parent~ attribute:
+
   #+begin_src c :tangle struct_hdf5.h
 typedef struct trexio_hdf5_s {
   trexio_t     parent ;
@@ -74,6 +79,21 @@ typedef struct trexio_hdf5_s {
 trexio_exit_code trexio_hdf5_init(trexio_t* const file);
 trexio_exit_code trexio_hdf5_deinit(trexio_t* const file);
 trexio_exit_code trexio_hdf5_inquire(const char* file_name);
+trexio_exit_code trexio_hdf5_flush(trexio_t* const file);
+  #+end_src
+
+  #+begin_src c :tangle basic_hdf5.c
+trexio_exit_code
+trexio_hdf5_flush(trexio_t* const file)
+{
+
+  trexio_hdf5_t* f = (trexio_hdf5_t*) file;
+
+  herr_t rc = H5Fflush(f->file_id, H5F_SCOPE_GLOBAL);
+  if (rc < 0) return TREXIO_FAILURE;
+
+  return TREXIO_SUCCESS;
+}
   #+end_src
 
   #+begin_src c :tangle basic_hdf5.c
@@ -174,6 +194,38 @@ trexio_hdf5_deinit (trexio_t* const file)
 }
   #+end_src
 
+* Template for HDF5 has a group
+
+  #+begin_src c :tangle hrw_group_hdf5.h :exports none
+trexio_exit_code trexio_hdf5_has_$group$ (trexio_t* const file);
+  #+end_src
+
+
+  #+begin_src c :tangle has_group_hdf5.c
+trexio_exit_code
+trexio_hdf5_has_$group$ (trexio_t* const file)
+{
+
+  if (file == NULL) return TREXIO_INVALID_ARG_1;
+
+  const trexio_hdf5_t* f = (const trexio_hdf5_t*) file;
+
+  struct H5G_info_t group_info;
+
+ /* H5Gget_info return info about the HDF5 group as a group_info struct */
+  herr_t status = H5Gget_info(f->$group$_group, &group_info);
+  if (status < 0) return TREXIO_FAILURE;
+
+ /* If nlinks==0 --> the group is empty, i.e. non-existent */
+  if (group_info.nlinks == (hsize_t) 0) {
+    return TREXIO_HAS_NOT;
+  } else {
+    return TREXIO_SUCCESS;
+  }
+
+}
+    #+end_src
+
 * Template for HDF5 has/read/write a numerical attribute
 
   #+begin_src c :tangle hrw_attr_num_hdf5.h :exports none
@@ -265,6 +317,7 @@ trexio_hdf5_has_$group_num$ (trexio_t* const file)
   if (file == NULL) return TREXIO_INVALID_ARG_1;
 
   const trexio_hdf5_t* f = (const trexio_hdf5_t*) file;
+  if (f->$group$_group == (hsize_t) 0) return TREXIO_HAS_NOT;
 
   htri_t status = H5Aexists(f->$group$_group, $GROUP_NUM$_NAME);
  /* H5Aexists returns positive value if attribute exists, 0 if does not, negative if error */
@@ -399,6 +452,7 @@ trexio_hdf5_has_$group_dset$ (trexio_t* const file)
   if (file == NULL) return TREXIO_INVALID_ARG_1;
 
   trexio_hdf5_t* f = (trexio_hdf5_t*) file;
+  if (f->$group$_group == (hsize_t) 0) return TREXIO_HAS_NOT;
 
   herr_t status = H5LTfind_dataset(f->$group$_group, $GROUP_DSET$_NAME);
  /* H5LTfind_dataset returns 1 if dataset exists, 0 otherwise */
@@ -441,7 +495,7 @@ trexio_hdf5_write_$group_dset$ (trexio_t* const file,
   trexio_hdf5_t* f = (trexio_hdf5_t*) file;
 
   hid_t index_dtype;
-  const void* index_p;
+  void* index_p = NULL;
   uint64_t size_ranked = (uint64_t) size * $group_dset_rank$;
  /* Determine the optimal type for storing indices depending on the size_max (usually mo_num or ao_num) */
   if (size_max < UINT8_MAX) {
@@ -461,7 +515,7 @@ trexio_hdf5_write_$group_dset$ (trexio_t* const file,
     index_p = index;
     index_dtype = H5T_NATIVE_UINT16;
   } else {
-    index_p = (const int32_t*) index_sparse;
+    index_p = (int32_t*) index_sparse;
     index_dtype = H5T_NATIVE_INT32;
   }
 
@@ -546,11 +600,11 @@ trexio_hdf5_read_$group_dset$ (trexio_t* const file,
   trexio_exit_code rc_read;
 
   // attempt to read indices
-  rc_read = trexio_hdf5_open_read_dset_sparse(f->$group$_group, dset_index_name, offset_i, count_i, NULL, is_index, index_read);
+  rc_read = trexio_hdf5_open_read_dset_sparse(f->$group$_group, dset_index_name, $group_dset_rank$, offset_i, count_i, NULL, is_index, index_read);
   if (rc_read != TREXIO_SUCCESS && rc_read != TREXIO_END) return rc_read;
   // attempt to read values
   // when EOF is encountered - the count_v[0] is modified and contains the number of elements being read
-  rc_read = trexio_hdf5_open_read_dset_sparse(f->$group$_group, dset_value_name, offset_v, count_v, eof_read_size, is_value, value_read);
+  rc_read = trexio_hdf5_open_read_dset_sparse(f->$group$_group, dset_value_name, 1, offset_v, count_v, eof_read_size, is_value, value_read);
   if (rc_read != TREXIO_SUCCESS && rc_read != TREXIO_END) return rc_read;
 
   return rc_read;
@@ -564,6 +618,7 @@ trexio_hdf5_read_$group_dset$_size (trexio_t* const file, int64_t* const size_ma
 {
 
   if (file == NULL) return TREXIO_INVALID_ARG_1;
+  if (size_max == NULL) return TREXIO_INVALID_ARG_2;
 
   const trexio_hdf5_t* f = (const trexio_hdf5_t*) file;
 
@@ -600,6 +655,7 @@ trexio_hdf5_has_$group_dset$ (trexio_t* const file)
   if (file == NULL) return TREXIO_INVALID_ARG_1;
 
   trexio_hdf5_t* f = (trexio_hdf5_t*) file;
+  if (f->$group$_group == (hsize_t) 0) return TREXIO_HAS_NOT;
 
   herr_t status = H5LTfind_dataset(f->$group$_group, $GROUP_DSET$_NAME "_values");
  /* H5LTfind_dataset returns 1 if dataset exists, 0 otherwise */
@@ -614,6 +670,141 @@ trexio_hdf5_has_$group_dset$ (trexio_t* const file)
 }
    #+end_src
 
+* Template for HDF5 has/read/write a dataset of buffered vectors
+
+   Chunked I/O in HDF5 for ~buffered~ data.
+
+   #+begin_src c :tangle hrw_buffered_hdf5.h :exports none
+trexio_exit_code trexio_hdf5_has_$group_dset$(trexio_t* const file);
+trexio_exit_code trexio_hdf5_read_$group_dset$(trexio_t* const file, const int64_t offset_file, const uint32_t rank, const uint64_t* dims, int64_t* const eof_read_size, double* const dset);
+trexio_exit_code trexio_hdf5_write_$group_dset$(trexio_t* const file, const int64_t offset_file, const uint32_t rank, const uint64_t* dims, const double* dset);
+trexio_exit_code trexio_hdf5_read_$group_dset$_size(trexio_t* const file, int64_t* const size_max);
+   #+end_src
+
+   #+begin_src c :tangle read_buffered_hdf5.c
+trexio_exit_code trexio_hdf5_read_$group_dset$(trexio_t* const file,
+                                               const int64_t offset_file,
+                                               const uint32_t rank,
+                                               const uint64_t* dims,
+                                               int64_t* const eof_read_size,
+                                               double* const dset)
+{
+  if (file == NULL) return TREXIO_INVALID_ARG_1;
+  if (eof_read_size == NULL) return TREXIO_INVALID_ARG_5;
+  if (dset == NULL) return TREXIO_INVALID_ARG_6;
+
+  const char dset_name[256] = "$group_dset$";
+
+  const trexio_hdf5_t* f = (const trexio_hdf5_t*) file;
+
+  hsize_t offset[1] = {(hsize_t) offset_file};
+  hsize_t count[1]  = {(hsize_t) dims[0]};
+
+  /* Attempt to read values (if EOF -> eof_read_size is modified with the number of elements read and return code is TREXIO_END)
+     0 argument below is requires to skip internal treatment specific to sparse indices (i.e. their de-compression).*/
+  return trexio_hdf5_open_read_dset_sparse(f->$group$_group, dset_name, 1, offset, count, eof_read_size, 0, dset);
+}
+   #+end_src
+
+   #+begin_src c :tangle write_buffered_hdf5.c
+trexio_exit_code trexio_hdf5_write_$group_dset$(trexio_t* const file,
+                                                const int64_t offset_file,
+		                                const uint32_t rank,
+                                                const uint64_t* dims,
+                                                const double* dset)
+{
+
+  if (file == NULL) return TREXIO_INVALID_ARG_1;
+  if (dset == NULL) return TREXIO_INVALID_ARG_5;
+
+  const char dset_name[256] = "$group_dset$";
+
+  trexio_hdf5_t* f = (trexio_hdf5_t*) file;
+
+  hid_t dtype = H5T_NATIVE_DOUBLE;
+
+ /* Arrays of chunk dims that will be used for chunking the dataset */
+  const hsize_t chunk_dims[1] = {(hsize_t) dims[0]};
+
+  trexio_exit_code rc_write = TREXIO_FAILURE;
+ /* NOTE: chunk size is set upon creation of the HDF5 dataset and cannot be changed ! */
+  if ( H5LTfind_dataset(f->$group$_group, dset_name) != 1 ) {
+ /* If the file does not exist -> create it and write */
+
+ /* Create chunked dataset with dtype datatype and write indices into it */
+    rc_write = trexio_hdf5_create_write_dset_sparse(f->$group$_group, dset_name, dtype, chunk_dims, dset);
+    if (rc_write != TREXIO_SUCCESS) return rc_write;
+
+  } else {
+ /* If the file exists -> open it and write */
+    hsize_t offset_data[1] = {(hsize_t) offset_file};
+
+ /* Create chunked dataset with dtype datatype and write indices into it */
+    rc_write = trexio_hdf5_open_write_dset_sparse(f->$group$_group, dset_name, dtype, chunk_dims, offset_data, dset);
+    if (rc_write != TREXIO_SUCCESS) return rc_write;
+
+  }
+
+  return TREXIO_SUCCESS;
+}
+
+trexio_exit_code
+trexio_hdf5_read_$group_dset$_size (trexio_t* const file, int64_t* const size_max)
+{
+
+  if (file == NULL) return TREXIO_INVALID_ARG_1;
+  if (size_max == NULL) return TREXIO_INVALID_ARG_2;
+
+  const char dset_name[256] = "$group_dset$";
+
+  const trexio_hdf5_t* f = (const trexio_hdf5_t*) file;
+
+  hid_t dset_id = H5Dopen(f->$group$_group, dset_name, H5P_DEFAULT);
+  if (dset_id <= 0) return TREXIO_INVALID_ID;
+
+  hid_t fspace_id = H5Dget_space(dset_id);
+  if (fspace_id < 0) {
+    H5Dclose(dset_id);
+    return TREXIO_INVALID_ID;
+  }
+
+  // allocate space for the dimensions to be read
+  hsize_t ddims[1] = {0};
+
+  // get the rank and dimensions of the dataset
+  H5Sget_simple_extent_dims(fspace_id, ddims, NULL);
+
+  H5Dclose(dset_id);
+  H5Sclose(fspace_id);
+
+  *size_max = (int64_t) ddims[0];
+
+  return TREXIO_SUCCESS;
+}
+   #+end_src
+
+   #+begin_src c :tangle has_buffered_hdf5.c
+trexio_exit_code trexio_hdf5_has_$group_dset$(trexio_t* const file)
+{
+  if (file == NULL) return TREXIO_INVALID_ARG_1;
+
+  trexio_hdf5_t* f = (trexio_hdf5_t*) file;
+  if (f->$group$_group == (hsize_t) 0) return TREXIO_HAS_NOT;
+
+  const char dset_name[256] = "$group_dset$";
+
+  herr_t status = H5LTfind_dataset(f->$group$_group, dset_name);
+ /* H5LTfind_dataset returns 1 if dataset exists, 0 otherwise */
+  if (status == 1){
+    return TREXIO_SUCCESS;
+  } else if (status == 0) {
+    return TREXIO_HAS_NOT;
+  } else {
+    return TREXIO_FAILURE;
+  }
+}
+   #+end_src
+
 * Template for HDF5 has/read/write a dataset of strings
 
    #+begin_src c :tangle hrw_dset_str_hdf5.h :exports none
@@ -798,6 +989,7 @@ trexio_hdf5_has_$group_dset$ (trexio_t* const file)
   if (file == NULL) return TREXIO_INVALID_ARG_1;
 
   trexio_hdf5_t* f = (trexio_hdf5_t*) file;
+  if (f->$group$_group == (hsize_t) 0) return TREXIO_HAS_NOT;
 
   herr_t status = H5LTfind_dataset(f->$group$_group, $GROUP_DSET$_NAME);
  /* H5LTfind_dataset returns 1 if dataset exists, 0 otherwise */
@@ -927,6 +1119,7 @@ trexio_hdf5_has_$group_str$ (trexio_t* const file)
   if (file == NULL) return TREXIO_INVALID_ARG_1;
 
   const trexio_hdf5_t* f = (const trexio_hdf5_t*) file;
+  if (f->$group$_group == (hsize_t) 0) return TREXIO_HAS_NOT;
 
   htri_t status = H5Aexists(f->$group$_group, $GROUP_STR$_NAME);
  /* H5Aexists returns positive value if attribute exists, 0 if does not, negative if error */
@@ -977,6 +1170,108 @@ trexio_hdf5_delete_$group$ (trexio_t* const file)
 }
    #+end_src
 
+* Source code for the determinant part
+
+   Each array is stored in a separate HDF5 dataset due to the fact that determinant I/O has to be decoupled.
+   Chunks are used to read/write the data to prevent memory overflow. Chunks have a given ~int64_t dims[0]*dims[1]~.
+   Size specifies the number of data items (e.g. determinants) to process.
+
+   #+begin_src c :tangle hrw_determinant_hdf5.h :exports none
+trexio_exit_code trexio_hdf5_has_determinant_list(trexio_t* const file);
+trexio_exit_code trexio_hdf5_read_determinant_list(trexio_t* const file, const int64_t offset_file, const uint32_t rank, const uint64_t* dims, int64_t* const eof_read_size, int64_t* const list);
+trexio_exit_code trexio_hdf5_write_determinant_list(trexio_t* const file, const int64_t offset_file, const uint32_t rank, const uint64_t* dims, const int64_t* list);
+   #+end_src
+
+   #+begin_src c :tangle read_determinant_hdf5.c
+trexio_exit_code trexio_hdf5_read_determinant_list(trexio_t* const file,
+                                                   const int64_t offset_file,
+                                                   const uint32_t rank,
+                                                   const uint64_t* dims,
+                                                   int64_t* const eof_read_size,
+                                                   int64_t* const list)
+{
+  if (file == NULL) return TREXIO_INVALID_ARG_1;
+  if (eof_read_size == NULL) return TREXIO_INVALID_ARG_5;
+  if (list == NULL) return TREXIO_INVALID_ARG_6;
+
+  const trexio_hdf5_t* f = (const trexio_hdf5_t*) file;
+
+  char dset_det_name[256] = "determinant_list";
+
+  hsize_t offset[1] = {(hsize_t) offset_file * dims[1]};
+  hsize_t count[1]  = {(hsize_t) dims[0] * dims[1]};
+
+  /* Attempt to read determinants (if EOF -> eof_read_size is modified with the number of elements read and return code is TREXIO_END)
+     0 argument below is requires to skip internal treatment specific to sparse indices (i.e. their de-compression).*/
+  return trexio_hdf5_open_read_dset_sparse(f->determinant_group, dset_det_name, (uint32_t) dims[1], offset, count, eof_read_size, 0, list);
+}
+   #+end_src
+
+   #+begin_src c :tangle write_determinant_hdf5.c
+trexio_exit_code trexio_hdf5_write_determinant_list(trexio_t* const file,
+                                                    const int64_t offset_file,
+		                                    const uint32_t rank,
+                                                    const uint64_t* dims,
+                                                    const int64_t* list)
+{
+
+  if (file == NULL) return TREXIO_INVALID_ARG_1;
+  if (list == NULL) return TREXIO_INVALID_ARG_5;
+
+  trexio_hdf5_t* f = (trexio_hdf5_t*) file;
+
+  hid_t det_dtype = H5T_NATIVE_INT64;
+  uint64_t size_ranked = dims[1]*dims[0];
+
+ /* Arrays of chunk dims that will be used for chunking the dataset */
+  const hsize_t chunk_dims[1] = {size_ranked};
+
+ /* Indices and values are stored as 2 independent datasets in the HDF5 file */
+  char dset_det_name[256] = "determinant_list";
+
+  trexio_exit_code rc_write = TREXIO_FAILURE;
+ /* NOTE: chunk size is set upon creation of the HDF5 dataset and cannot be changed ! */
+  if ( H5LTfind_dataset(f->determinant_group, dset_det_name) != 1 ) {
+ /* If the file does not exist -> create it and write */
+
+ /* Create chunked dataset with det_dtype datatype and write indices into it */
+    rc_write = trexio_hdf5_create_write_dset_sparse(f->determinant_group, dset_det_name, det_dtype, chunk_dims, list);
+    if (rc_write != TREXIO_SUCCESS) return rc_write;
+
+  } else {
+ /* If the file exists -> open it and write */
+    hsize_t offset_data[1] = {(hsize_t) offset_file * dims[1]};
+
+ /* Create chunked dataset with det_dtype datatype and write indices into it */
+    rc_write = trexio_hdf5_open_write_dset_sparse(f->determinant_group, dset_det_name, det_dtype, chunk_dims, offset_data, list);
+    if (rc_write != TREXIO_SUCCESS) return rc_write;
+
+  }
+
+  return TREXIO_SUCCESS;
+}
+   #+end_src
+
+   #+begin_src c :tangle has_determinant_hdf5.c
+trexio_exit_code trexio_hdf5_has_determinant_list(trexio_t* const file)
+{
+  if (file == NULL) return TREXIO_INVALID_ARG_1;
+
+  trexio_hdf5_t* f = (trexio_hdf5_t*) file;
+  if (f->determinant_group == (hsize_t) 0) return TREXIO_HAS_NOT;
+
+  herr_t status = H5LTfind_dataset(f->determinant_group, "determinant_list");
+ /* H5LTfind_dataset returns 1 if dataset exists, 0 otherwise */
+  if (status == 1){
+    return TREXIO_SUCCESS;
+  } else if (status == 0) {
+    return TREXIO_HAS_NOT;
+  } else {
+    return TREXIO_FAILURE;
+  }
+}
+   #+end_src
+
 * Helper functions
 
   #+begin_src c :tangle helpers_hdf5.c
@@ -1113,6 +1408,7 @@ trexio_hdf5_open_write_dset_sparse (const hid_t group_id,
 trexio_exit_code
 trexio_hdf5_open_read_dset_sparse (const hid_t group_id,
                                    const char* dset_name,
+                                   const uint32_t dset_rank,
                                    const hsize_t* offset_file,
                                    hsize_t* const size_read,
                                    int64_t* const eof_read_size,
@@ -1121,6 +1417,7 @@ trexio_hdf5_open_read_dset_sparse (const hid_t group_id,
                                    )
 {
   const int h5_rank = 1;
+  if (dset_rank == 0) return TREXIO_INVALID_ARG_3;
 
   // get the dataset handle
   hid_t dset_id = H5Dopen(group_id, dset_name, H5P_DEFAULT);
@@ -1151,9 +1448,9 @@ trexio_hdf5_open_read_dset_sparse (const hid_t group_id,
   if (max_offset > ddims[0]) {
     is_EOF = 1;
     // lower the value of count to reduce the number of elements which will be read
-    size_read[0] -= max_offset - ddims[0];
+    size_read[0] -= (max_offset - ddims[0]);
     // modified the value of eof_read_size passed by address
-    if (eof_read_size != NULL) *eof_read_size = size_read[0];
+    if (eof_read_size != NULL) *eof_read_size = size_read[0]/dset_rank;
   }
 
   // special case when reading int indices
@@ -1238,7 +1535,7 @@ trexio_hdf5_open_read_dset_sparse (const hid_t group_id,
   #+begin_src c :tangle suffix_hdf5.h
 trexio_exit_code trexio_hdf5_create_write_dset_sparse (const hid_t group_id, const char* dset_name, const hid_t dtype_id, const hsize_t* chunk_dims, const void* data_sparse);
 trexio_exit_code trexio_hdf5_open_write_dset_sparse (const hid_t group_id, const char* dset_name, const hid_t dtype_id, const hsize_t* chunk_dims, const hsize_t* offset_file, const void* data_sparse);
-trexio_exit_code trexio_hdf5_open_read_dset_sparse (const hid_t group_id, const char* dset_name, const hsize_t* offset_file, hsize_t* const size_read, int64_t* const eof_read_size, const int is_index, void* const data_sparse);
+trexio_exit_code trexio_hdf5_open_read_dset_sparse (const hid_t group_id, const char* dset_name, const uint32_t dset_rank, const hsize_t* offset_file, hsize_t* const size_read, int64_t* const eof_read_size, const int is_index, void* const data_sparse);
 
 #endif
   #+end_src

src/templates_text/build.sh

@@ -10,6 +10,12 @@ cat populated/pop_struct_text_group_dset.h >> trexio_text.h
 cat populated/pop_struct_text_group.h >> trexio_text.h
 cat basic_text.h   >> trexio_text.h
 
+cat hrw_determinant_text.h >> trexio_text.h
+cat *_determinant_text.c >> trexio_text.c
+
+cat populated/pop_has_group_text.c >> trexio_text.c
+cat populated/pop_hrw_group_text.h >> trexio_text.h
+
 cat populated/pop_free_group_text.c >> trexio_text.c
 cat populated/pop_read_group_text.c >> trexio_text.c
 cat populated/pop_flush_group_text.c >> trexio_text.c
@@ -24,23 +30,27 @@ cat populated/pop_has_dset_str_text.c >> trexio_text.c
 cat populated/pop_has_dset_sparse_text.c >> trexio_text.c
 cat populated/pop_has_attr_num_text.c >> trexio_text.c
 cat populated/pop_has_attr_str_text.c >> trexio_text.c
+cat populated/pop_has_buffered_text.c >> trexio_text.c
 
 cat populated/pop_read_dset_data_text.c >> trexio_text.c
 cat populated/pop_read_dset_str_text.c >> trexio_text.c
 cat populated/pop_read_dset_sparse_text.c >> trexio_text.c
 cat populated/pop_read_attr_str_text.c >> trexio_text.c
 cat populated/pop_read_attr_num_text.c >> trexio_text.c
+cat populated/pop_read_buffered_text.c >> trexio_text.c
 
 cat populated/pop_write_dset_data_text.c >> trexio_text.c
 cat populated/pop_write_dset_str_text.c >> trexio_text.c
 cat populated/pop_write_dset_sparse_text.c >> trexio_text.c
 cat populated/pop_write_attr_str_text.c >> trexio_text.c
 cat populated/pop_write_attr_num_text.c >> trexio_text.c
+cat populated/pop_write_buffered_text.c >> trexio_text.c
 
 cat populated/pop_hrw_dset_data_text.h >> trexio_text.h
 cat populated/pop_hrw_dset_str_text.h >> trexio_text.h
 cat populated/pop_hrw_dset_sparse_text.h >> trexio_text.h
 cat populated/pop_hrw_attr_num_text.h >> trexio_text.h
 cat populated/pop_hrw_attr_str_text.h >> trexio_text.h
+cat populated/pop_hrw_buffered_text.h >> trexio_text.h
 
 cat suffix_text.h   >> trexio_text.h

tests/CMakeLists.txt

@@ -7,6 +7,7 @@ set(Tests_text
   io_dset_float_text
   io_dset_str_text
   io_dset_sparse_text
+  io_determinant_text
   io_safe_dset_float_text
   io_dset_int_text
   io_num_text
@@ -23,6 +24,7 @@ if(ENABLE_HDF5)
     io_dset_float_hdf5
     io_dset_str_hdf5
     io_dset_sparse_hdf5
+    io_determinant_hdf5
     io_safe_dset_float_hdf5
     io_dset_int_hdf5
     io_num_hdf5

tests/delete_group_text.c

@@ -5,7 +5,7 @@
 
 #define TEST_BACKEND 	TREXIO_TEXT
 #define TREXIO_FILE 	"test_del.dir"
-#define RM_COMMAND 	"rm -rf " TREXIO_FILE
+#define RM_COMMAND 	"rm -f -- " TREXIO_FILE "/*.txt " TREXIO_FILE "/*.txt.size " TREXIO_FILE "/.lock && rm -fd -- " TREXIO_FILE
 
 static int test_write_delete_group (const char* file_name, const back_end_t backend) {
 

tests/io_all.c

@@ -26,11 +26,11 @@ int main() {
     assert (rc == 0);
   }
 
-  rc = system("rm -rf test_all.dir");
+  rc = system("rm -f -- test_all.dir/*.txt test_all.dir/*.txt.size test_all.dir/.lock && rm -fd -- test_all.dir");
   assert (rc == 0);
   test_write("test_all.dir", TREXIO_TEXT);
   test_read ("test_all.dir", TREXIO_TEXT);
-  rc = system("rm -rf test_all.dir");
+  rc = system("rm -f -- test_all.dir/*.txt test_all.dir/*.txt.size test_all.dir/.lock && rm -fd -- test_all.dir");
   assert (rc == 0);
 
   return 0;
@@ -94,6 +94,10 @@ int test_write(const char* file_name, const back_end_t backend) {
   rc = trexio_write_nucleus_coord(file,coord);
   assert (rc == TREXIO_SUCCESS);
 
+  // check the force flushing
+  rc = trexio_flush(file);
+  assert (rc == TREXIO_SUCCESS);
+
   rc = trexio_write_nucleus_label(file, label, 32);
   assert (rc == TREXIO_SUCCESS);
   rc = trexio_write_nucleus_point_group(file, sym, 32);

tests/io_determinant_hdf5.c

@@ -0,0 +1,326 @@
+#include "trexio.h"
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+#define TEST_BACKEND  TREXIO_HDF5
+#define TREXIO_FILE   "test_determinant.h5"
+#define RM_COMMAND    "rm -f -- " TREXIO_FILE
+#define SIZE          100
+#define N_CHUNKS      5
+#define STATE_TEST    2
+#define MO_NUM        150
+
+static int test_write_determinant (const char* file_name, const back_end_t backend, const int64_t offset) {
+
+/* Try to write an array of sparse data into the TREXIO file */
+
+  trexio_t* file = NULL;
+  trexio_exit_code rc;
+
+/*================= START OF TEST ==================*/
+
+  // open file in 'write' mode
+  file = trexio_open(file_name, 'w', backend, &rc);
+  assert (file != NULL);
+  assert (rc == TREXIO_SUCCESS);
+
+  // parameters to be written
+  int64_t* det_list;
+  double*  det_coef;
+
+  int mo_num = MO_NUM;
+
+  // write mo_num which will be used to determine the optimal size of int indices
+  if (trexio_has_mo_num(file) == TREXIO_HAS_NOT) {
+    rc = trexio_write_mo_num(file, mo_num);
+    assert(rc == TREXIO_SUCCESS);
+  }
+
+  // get the number of int64 bit fields per determinant
+  int int_num;
+  rc = trexio_get_int64_num(file, &int_num);
+  assert(rc == TREXIO_SUCCESS);
+  assert(int_num == (MO_NUM-1)/64 + 1);
+
+  // allocate memory and fill with values to be written
+  det_list = (int64_t*) calloc(2 * int_num * SIZE, sizeof(int64_t));
+  det_coef = (double*) calloc(SIZE, sizeof(double));
+
+  for(int i=0; i<SIZE; i++){
+    det_list[6*i]   = 6*i;
+    det_list[6*i+1] = 6*i+1;
+    det_list[6*i+2] = 6*i+2;
+    det_list[6*i+3] = 6*i+3;
+    det_list[6*i+4] = 6*i+4;
+    det_list[6*i+5] = 6*i+5;
+    det_coef[i]     = 3.14 + (double) i;
+  }
+
+  // write dataset chunks of sparse data in the file (including FAKE statements)
+  uint64_t chunk_size = (uint64_t) SIZE/N_CHUNKS;
+  uint64_t offset_f = 0UL;
+  uint64_t offset_d = 0UL;
+  if (offset != 0L) offset_f += offset;
+
+  // write the state_id of a given file: 0 is ground state
+  if (trexio_has_state_id(file) == TREXIO_HAS_NOT) {
+    rc = trexio_write_state_id(file, STATE_TEST);
+    assert(rc == TREXIO_SUCCESS);
+  }
+
+  // write n_chunks times using write_sparse
+  for(int i=0; i<N_CHUNKS; ++i){
+
+    rc = trexio_write_determinant_list(file, offset_f, chunk_size, &det_list[2*int_num*offset_d]);
+    assert(rc == TREXIO_SUCCESS);
+
+    rc = trexio_write_determinant_coefficient(file, offset_f, chunk_size, &det_coef[offset_d]);
+    assert(rc == TREXIO_SUCCESS);
+
+    offset_d += chunk_size;
+    offset_f += chunk_size;
+  }
+
+  // manually check the consistency of the determinant_num and coefficient_size after writing
+  int64_t coeff_size = 0L;
+  int64_t determinant_num = 0L;
+
+  rc = trexio_read_determinant_num_64(file, &determinant_num);
+  assert(rc == TREXIO_SUCCESS);
+
+  rc = trexio_read_determinant_coefficient_size(file, &coeff_size);
+  assert(rc == TREXIO_SUCCESS);
+  assert(determinant_num == coeff_size);
+
+  // close current session
+  rc = trexio_close(file);
+  assert (rc == TREXIO_SUCCESS);
+
+  // free the allocated memeory
+  free(det_list);
+  free(det_coef);
+
+/*================= END OF TEST ==================*/
+
+  return 0;
+}
+
+static int test_has_determinant(const char* file_name, const back_end_t backend) {
+
+/* Try to check the existence of a dataset of sparse data in the TREXIO file */
+
+  trexio_t* file = NULL;
+  trexio_exit_code rc;
+
+/*================= START OF TEST ==================*/
+
+  // open file
+  file = trexio_open(file_name, 'r', backend, &rc);
+  assert (file != NULL);
+  assert (rc == TREXIO_SUCCESS);
+
+  // now check that previously written determinant_list exists
+  rc = trexio_has_determinant_list(file);
+  assert(rc==TREXIO_SUCCESS);
+
+  rc = trexio_has_state_id(file);
+  assert(rc==TREXIO_SUCCESS);
+
+  // now check that previously written determinant_coefficient exists
+  rc = trexio_has_determinant_coefficient(file);
+  assert(rc==TREXIO_SUCCESS);
+
+  // close current session
+  rc = trexio_close(file);
+  assert (rc == TREXIO_SUCCESS);
+
+/*================= END OF TEST ==================*/
+
+  return 0;
+}
+
+static int test_read_determinant (const char* file_name, const back_end_t backend, const int64_t offset) {
+
+/* Try to read one chunk of dataset of sparse data in the TREXIO file */
+
+  trexio_t* file = NULL;
+  trexio_exit_code rc;
+
+/*================= START OF TEST ==================*/
+
+  // open file
+  file = trexio_open(file_name, 'r', backend, &rc);
+  assert (file != NULL);
+  assert (rc == TREXIO_SUCCESS);
+
+  // compute how many integer bit fields is needed per determinant (for a given spin)
+  int64_t mo_num;
+  rc = trexio_read_mo_num_64(file, &mo_num);
+  assert (rc == TREXIO_SUCCESS);
+  assert (mo_num == MO_NUM);
+
+  int int_num;
+  rc = trexio_get_int64_num(file, &int_num);
+  assert (rc == TREXIO_SUCCESS);
+  assert (int_num == (MO_NUM - 1)/64 + 1);
+
+  // define arrays to read into
+  int64_t* det_list_read;
+  double*  det_coef_read;
+  double check_diff;
+  uint64_t size_r = 40L;
+
+  det_list_read = (int64_t*) calloc(2*int_num*size_r,sizeof(int64_t));
+  det_coef_read = (double*)  calloc(size_r,sizeof(double));
+
+  // specify the read parameters, here:
+  // 1 chunk of 10 elements using offset of 40 (i.e. lines No. 40--59) into elements of the array starting from 5
+  int64_t chunk_read = 10L;
+  int64_t offset_file_read = 40L;
+  int offset_data_read = 5;
+  int64_t read_size_check;
+  read_size_check = chunk_read;
+
+  if (offset != 0L) offset_file_read += offset;
+
+  // read one chunk using the aforementioned parameters
+  rc = trexio_read_determinant_list(file, offset_file_read, &chunk_read, &det_list_read[2*int_num*offset_data_read]);
+  assert(rc == TREXIO_SUCCESS);
+  assert(chunk_read == read_size_check);
+  assert(det_list_read[0] == 0);
+  assert(det_list_read[2*int_num*offset_data_read] == 2 * int_num * (int64_t) (offset_file_read-offset));
+
+  rc = trexio_read_determinant_coefficient(file, offset_file_read, &chunk_read, &det_coef_read[offset_data_read]);
+  assert(rc == TREXIO_SUCCESS);
+  assert(chunk_read == read_size_check);
+
+  check_diff = det_coef_read[0] - 0.;
+  assert(check_diff*check_diff < 1e-14);
+
+  check_diff = det_coef_read[offset_data_read] - (3.14 + (double) (offset_file_read-offset));
+  //printf("%lf %lf\n", check_diff, det_coef_read[offset_data_read]);
+  assert(check_diff*check_diff < 1e-14);
+
+  int32_t state_id = 666;
+  rc = trexio_read_state_id(file, &state_id);
+  assert(rc == TREXIO_SUCCESS);
+  assert(state_id == STATE_TEST);
+
+  // now attempt to read so that one encounters end of file during reading (i.e. offset_file_read + chunk_read > size_max)
+  offset_file_read = 97L;
+  offset_data_read = 1;
+  int64_t eof_read_size_check = SIZE - offset_file_read; // if offset_file_read=97 => only 3 integrals will be read out of total of 100
+
+  if (offset != 0L) offset_file_read += offset;
+
+  chunk_read = read_size_check;
+  // read one chunk that will reach EOF and return TREXIO_END code
+  rc = trexio_read_determinant_list(file, offset_file_read, &chunk_read, &det_list_read[2*int_num*offset_data_read]);
+  /*
+  printf("%s\n", trexio_string_of_error(rc));
+  for (int i=0; i<size_r; i++) {
+    printf("%lld %lld\n", det_list_read[6*i], det_list_read[6*i+5]);
+  }
+  */
+  assert(rc == TREXIO_END);
+  assert(chunk_read == eof_read_size_check);
+  assert(det_list_read[2*int_num*size_r-1] == 0);
+  assert(det_list_read[2*int_num*offset_data_read] == 2 * int_num * (int64_t) (offset_file_read-offset));
+
+  chunk_read = read_size_check;
+  rc = trexio_read_determinant_coefficient(file, offset_file_read, &chunk_read, &det_coef_read[offset_data_read]);
+  /*
+  printf("%s\n", trexio_string_of_error(rc));
+  for (int i=0; i<size_r; i++) {
+    printf("%lf\n", det_coef_read[i]);
+  }
+  */
+  assert(rc == TREXIO_END);
+  assert(chunk_read == eof_read_size_check);
+
+  check_diff= det_coef_read[size_r-1] - 0.;
+  //printf("%lf %lf\n", check_diff, det_coef_read[size_r-1]);
+  assert(check_diff*check_diff < 1e-14);
+
+  // check the value of determinant_num
+  int32_t det_num = 0;
+  int32_t size_check = SIZE;
+  if (offset != 0L) size_check += offset;
+
+  rc = trexio_read_determinant_num(file, &det_num);
+  assert(rc == TREXIO_SUCCESS);
+  assert(det_num == size_check);
+
+  // check conversion of determinants into orbital lists
+  int64_t  size_list = TREXIO_NORB_PER_INT * int_num;
+  int32_t* orb_list_up = (int32_t*) calloc(size_list, sizeof(int32_t));
+  int32_t* orb_list_dn = (int32_t*) calloc(size_list, sizeof(int32_t));
+  int32_t  occ_num_up, occ_num_dn;
+
+  rc = trexio_to_orbital_list_up_dn (int_num, &det_list_read[2*int_num*5], orb_list_up, orb_list_dn, &occ_num_up, &occ_num_dn);
+  assert (rc == TREXIO_SUCCESS);
+  assert (occ_num_up == 14);
+  assert (occ_num_dn == 17);
+  /* // DEBUG printing
+  printf("occ_num_up : %d ; occ_num_dn : %d \n", occ_num_up, occ_num_dn);
+  for (int i=0; i<occ_num_up; i++) {
+     printf("%d ", orb_list_up[i]);
+  }
+  printf("| ");
+  for (int i=0; i<occ_num_dn; i++) {
+     printf("%d ", orb_list_dn[i]);
+  }
+  printf("\n");
+  */
+
+  // check conversion of one orbital list into the bitfield determinant representation
+  int64_t* det_list_check = (int64_t*) calloc(int_num, sizeof(int64_t));
+
+  rc = trexio_to_bitfield_list (orb_list_up, occ_num_up, det_list_check, int_num);
+  assert (rc == TREXIO_SUCCESS);
+  for (int i=0; i<int_num; i++) {
+    assert (det_list_check[i] == det_list_read[2*int_num*5+i]);
+  }
+
+  // close current session
+  rc = trexio_close(file);
+  assert (rc == TREXIO_SUCCESS);
+
+  // free the memory
+  free(det_list_read);
+  free(det_coef_read);
+  free(det_list_check);
+  free(orb_list_up);
+  free(orb_list_dn);
+
+/*================= END OF TEST ==================*/
+
+  return 0;
+}
+
+
+int main(){
+
+/*============== Test launcher ================*/
+
+  int rc;
+
+  rc = system(RM_COMMAND);
+  assert (rc == 0);
+
+  // check the first write attempt (SIZE elements written in N_CHUNKS chunks)
+  test_write_determinant (TREXIO_FILE, TEST_BACKEND, 0);
+  test_has_determinant   (TREXIO_FILE, TEST_BACKEND);
+  test_read_determinant  (TREXIO_FILE, TEST_BACKEND, 0);
+
+  // check the second write attempt (SIZE elements written in N_CHUNKS chunks)
+  test_write_determinant (TREXIO_FILE, TEST_BACKEND, SIZE);
+  test_read_determinant  (TREXIO_FILE, TEST_BACKEND, SIZE);
+
+  rc = system(RM_COMMAND);
+  assert (rc == 0);
+
+  return 0;
+}

tests/io_determinant_text.c

@@ -0,0 +1,326 @@
+#include "trexio.h"
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+#define TEST_BACKEND  TREXIO_TEXT
+#define TREXIO_FILE   "test_determinant.dir"
+#define RM_COMMAND    "rm -f -- " TREXIO_FILE "/*.txt " TREXIO_FILE "/*.txt.size " TREXIO_FILE "/.lock && rm -fd -- " TREXIO_FILE
+#define SIZE          100
+#define N_CHUNKS      5
+#define STATE_TEST    2
+#define MO_NUM        150
+
+static int test_write_determinant (const char* file_name, const back_end_t backend, const int64_t offset) {
+
+/* Try to write an array of sparse data into the TREXIO file */
+
+  trexio_t* file = NULL;
+  trexio_exit_code rc;
+
+/*================= START OF TEST ==================*/
+
+  // open file in 'write' mode
+  file = trexio_open(file_name, 'w', backend, &rc);
+  assert (file != NULL);
+  assert (rc == TREXIO_SUCCESS);
+
+  // parameters to be written
+  int64_t* det_list;
+  double*  det_coef;
+
+  int mo_num = MO_NUM;
+
+  // write mo_num which will be used to determine the optimal size of int indices
+  if (trexio_has_mo_num(file) == TREXIO_HAS_NOT) {
+    rc = trexio_write_mo_num(file, mo_num);
+    assert(rc == TREXIO_SUCCESS);
+  }
+
+  // get the number of int64 bit fields per determinant
+  int int_num;
+  rc = trexio_get_int64_num(file, &int_num);
+  assert(rc == TREXIO_SUCCESS);
+  assert(int_num == (MO_NUM-1)/64 + 1);
+
+  // allocate memory and fill with values to be written
+  det_list = (int64_t*) calloc(2 * int_num * SIZE, sizeof(int64_t));
+  det_coef = (double*) calloc(SIZE, sizeof(double));
+
+  for(int i=0; i<SIZE; i++){
+    det_list[6*i]   = 6*i;
+    det_list[6*i+1] = 6*i+1;
+    det_list[6*i+2] = 6*i+2;
+    det_list[6*i+3] = 6*i+3;
+    det_list[6*i+4] = 6*i+4;
+    det_list[6*i+5] = 6*i+5;
+    det_coef[i]     = 3.14 + (double) i;
+  }
+
+  // write dataset chunks of sparse data in the file (including FAKE statements)
+  uint64_t chunk_size = (uint64_t) SIZE/N_CHUNKS;
+  uint64_t offset_f = 0UL;
+  uint64_t offset_d = 0UL;
+  if (offset != 0L) offset_f += offset;
+
+  // write the state_id of a given file: 0 is ground state
+  if (trexio_has_state_id(file) == TREXIO_HAS_NOT) {
+    rc = trexio_write_state_id(file, STATE_TEST);
+    assert(rc == TREXIO_SUCCESS);
+  }
+
+  // write n_chunks times using write_sparse
+  for(int i=0; i<N_CHUNKS; ++i){
+
+    rc = trexio_write_determinant_list(file, offset_f, chunk_size, &det_list[2*int_num*offset_d]);
+    assert(rc == TREXIO_SUCCESS);
+
+    rc = trexio_write_determinant_coefficient(file, offset_f, chunk_size, &det_coef[offset_d]);
+    assert(rc == TREXIO_SUCCESS);
+
+    offset_d += chunk_size;
+    offset_f += chunk_size;
+  }
+
+  // manually check the consistency of the determinant_num and coefficient_size after writing
+  int64_t coeff_size = 0L;
+  int64_t determinant_num = 0L;
+
+  rc = trexio_read_determinant_num_64(file, &determinant_num);
+  assert(rc == TREXIO_SUCCESS);
+
+  rc = trexio_read_determinant_coefficient_size(file, &coeff_size);
+  assert(rc == TREXIO_SUCCESS);
+  assert(determinant_num == coeff_size);
+
+  // close current session
+  rc = trexio_close(file);
+  assert (rc == TREXIO_SUCCESS);
+
+  // free the allocated memeory
+  free(det_list);
+  free(det_coef);
+
+/*================= END OF TEST ==================*/
+
+  return 0;
+}
+
+static int test_has_determinant(const char* file_name, const back_end_t backend) {
+
+/* Try to check the existence of a dataset of sparse data in the TREXIO file */
+
+  trexio_t* file = NULL;
+  trexio_exit_code rc;
+
+/*================= START OF TEST ==================*/
+
+  // open file
+  file = trexio_open(file_name, 'r', backend, &rc);
+  assert (file != NULL);
+  assert (rc == TREXIO_SUCCESS);
+
+  // now check that previously written determinant_list exists
+  rc = trexio_has_determinant_list(file);
+  assert(rc==TREXIO_SUCCESS);
+
+  rc = trexio_has_state_id(file);
+  assert(rc==TREXIO_SUCCESS);
+
+  // now check that previously written determinant_coefficient exists
+  rc = trexio_has_determinant_coefficient(file);
+  assert(rc==TREXIO_SUCCESS);
+
+  // close current session
+  rc = trexio_close(file);
+  assert (rc == TREXIO_SUCCESS);
+
+/*================= END OF TEST ==================*/
+
+  return 0;
+}
+
+static int test_read_determinant (const char* file_name, const back_end_t backend, const int64_t offset) {
+
+/* Try to read one chunk of dataset of sparse data in the TREXIO file */
+
+  trexio_t* file = NULL;
+  trexio_exit_code rc;
+
+/*================= START OF TEST ==================*/
+
+  // open file
+  file = trexio_open(file_name, 'r', backend, &rc);
+  assert (file != NULL);
+  assert (rc == TREXIO_SUCCESS);
+
+  // compute how many integer bit fields is needed per determinant (for a given spin)
+  int64_t mo_num;
+  rc = trexio_read_mo_num_64(file, &mo_num);
+  assert (rc == TREXIO_SUCCESS);
+  assert (mo_num == MO_NUM);
+
+  int int_num;
+  rc = trexio_get_int64_num(file, &int_num);
+  assert (rc == TREXIO_SUCCESS);
+  assert (int_num == (MO_NUM - 1)/64 + 1);
+
+  // define arrays to read into
+  int64_t* det_list_read;
+  double*  det_coef_read;
+  double check_diff;
+  uint64_t size_r = 40L;
+
+  det_list_read = (int64_t*) calloc(2*int_num*size_r,sizeof(int64_t));
+  det_coef_read = (double*)  calloc(size_r,sizeof(double));
+
+  // specify the read parameters, here:
+  // 1 chunk of 10 elements using offset of 40 (i.e. lines No. 40--59) into elements of the array starting from 5
+  int64_t chunk_read = 10L;
+  int64_t offset_file_read = 40L;
+  int offset_data_read = 5;
+  int64_t read_size_check;
+  read_size_check = chunk_read;
+
+  if (offset != 0L) offset_file_read += offset;
+
+  // read one chunk using the aforementioned parameters
+  rc = trexio_read_determinant_list(file, offset_file_read, &chunk_read, &det_list_read[2*int_num*offset_data_read]);
+  assert(rc == TREXIO_SUCCESS);
+  assert(chunk_read == read_size_check);
+  assert(det_list_read[0] == 0);
+  assert(det_list_read[2*int_num*offset_data_read] == 2 * int_num * (int64_t) (offset_file_read-offset));
+
+  rc = trexio_read_determinant_coefficient(file, offset_file_read, &chunk_read, &det_coef_read[offset_data_read]);
+  assert(rc == TREXIO_SUCCESS);
+  assert(chunk_read == read_size_check);
+
+  check_diff = det_coef_read[0] - 0.;
+  assert(check_diff*check_diff < 1e-14);
+
+  check_diff = det_coef_read[offset_data_read] - (3.14 + (double) (offset_file_read-offset));
+  //printf("%lf %lf\n", check_diff, det_coef_read[offset_data_read]);
+  assert(check_diff*check_diff < 1e-14);
+
+  int32_t state_id = 666;
+  rc = trexio_read_state_id(file, &state_id);
+  assert(rc == TREXIO_SUCCESS);
+  assert(state_id == STATE_TEST);
+
+  // now attempt to read so that one encounters end of file during reading (i.e. offset_file_read + chunk_read > size_max)
+  offset_file_read = 97L;
+  offset_data_read = 1;
+  int64_t eof_read_size_check = SIZE - offset_file_read; // if offset_file_read=97 => only 3 integrals will be read out of total of 100
+
+  if (offset != 0L) offset_file_read += offset;
+
+  chunk_read = read_size_check;
+  // read one chunk that will reach EOF and return TREXIO_END code
+  rc = trexio_read_determinant_list(file, offset_file_read, &chunk_read, &det_list_read[2*int_num*offset_data_read]);
+  /*
+  printf("%s\n", trexio_string_of_error(rc));
+  for (int i=0; i<size_r; i++) {
+    printf("%lld %lld\n", det_list_read[6*i], det_list_read[6*i+5]);
+  }
+  */
+  assert(rc == TREXIO_END);
+  assert(chunk_read == eof_read_size_check);
+  assert(det_list_read[2*int_num*size_r-1] == 0);
+  assert(det_list_read[2*int_num*offset_data_read] == 2 * int_num * (int64_t) (offset_file_read-offset));
+
+  chunk_read = read_size_check;
+  rc = trexio_read_determinant_coefficient(file, offset_file_read, &chunk_read, &det_coef_read[offset_data_read]);
+  /*
+  printf("%s\n", trexio_string_of_error(rc));
+  for (int i=0; i<size_r; i++) {
+    printf("%lf\n", det_coef_read[i]);
+  }
+  */
+  assert(rc == TREXIO_END);
+  assert(chunk_read == eof_read_size_check);
+
+  check_diff= det_coef_read[size_r-1] - 0.;
+  //printf("%lf %lf\n", check_diff, det_coef_read[size_r-1]);
+  assert(check_diff*check_diff < 1e-14);
+
+  // check the value of determinant_num
+  int32_t det_num = 0;
+  int32_t size_check = SIZE;
+  if (offset != 0L) size_check += offset;
+
+  rc = trexio_read_determinant_num(file, &det_num);
+  assert(rc == TREXIO_SUCCESS);
+  assert(det_num == size_check);
+
+  // check conversion of determinants into orbital lists
+  int64_t  size_list = TREXIO_NORB_PER_INT * int_num;
+  int32_t* orb_list_up = (int32_t*) calloc(size_list, sizeof(int32_t));
+  int32_t* orb_list_dn = (int32_t*) calloc(size_list, sizeof(int32_t));
+  int32_t  occ_num_up, occ_num_dn;
+
+  rc = trexio_to_orbital_list_up_dn (int_num, &det_list_read[2*int_num*5], orb_list_up, orb_list_dn, &occ_num_up, &occ_num_dn);
+  assert (rc == TREXIO_SUCCESS);
+  assert (occ_num_up == 14);
+  assert (occ_num_dn == 17);
+  /* // DEBUG printing
+  printf("occ_num_up : %d ; occ_num_dn : %d \n", occ_num_up, occ_num_dn);
+  for (int i=0; i<occ_num_up; i++) {
+     printf("%d ", orb_list_up[i]);
+  }
+  printf("| ");
+  for (int i=0; i<occ_num_dn; i++) {
+     printf("%d ", orb_list_dn[i]);
+  }
+  printf("\n");
+  */
+
+  // check conversion of one orbital list into the bitfield determinant representation
+  int64_t* det_list_check = (int64_t*) calloc(int_num, sizeof(int64_t));
+
+  rc = trexio_to_bitfield_list (orb_list_up, occ_num_up, det_list_check, int_num);
+  assert (rc == TREXIO_SUCCESS);
+  for (int i=0; i<int_num; i++) {
+    assert (det_list_check[i] == det_list_read[2*int_num*5+i]);
+  }
+
+  // close current session
+  rc = trexio_close(file);
+  assert (rc == TREXIO_SUCCESS);
+
+  // free the memory
+  free(det_list_read);
+  free(det_coef_read);
+  free(det_list_check);
+  free(orb_list_up);
+  free(orb_list_dn);
+
+/*================= END OF TEST ==================*/
+
+  return 0;
+}
+
+
+int main(){
+
+/*============== Test launcher ================*/
+
+  int rc;
+
+  rc = system(RM_COMMAND);
+  assert (rc == 0);
+
+  // check the first write attempt (SIZE elements written in N_CHUNKS chunks)
+  test_write_determinant (TREXIO_FILE, TEST_BACKEND, 0);
+  test_has_determinant   (TREXIO_FILE, TEST_BACKEND);
+  test_read_determinant  (TREXIO_FILE, TEST_BACKEND, 0);
+
+  // check the second write attempt (SIZE elements written in N_CHUNKS chunks)
+  test_write_determinant (TREXIO_FILE, TEST_BACKEND, SIZE);
+  test_read_determinant  (TREXIO_FILE, TEST_BACKEND, SIZE);
+
+  rc = system(RM_COMMAND);
+  assert (rc == 0);
+
+  return 0;
+}

tests/io_dset_float_text.c

@@ -5,7 +5,7 @@
 
 #define TEST_BACKEND 	TREXIO_TEXT
 #define TREXIO_FILE 	"test_dset_f.dir"
-#define RM_COMMAND 	"rm -rf " TREXIO_FILE
+#define RM_COMMAND 	"rm -f -- " TREXIO_FILE "/*.txt " TREXIO_FILE "/*.txt.size " TREXIO_FILE "/.lock && rm -fd -- " TREXIO_FILE
 
 static int test_write_dset (const char* file_name, const back_end_t backend) {
 
@@ -40,7 +40,7 @@ static int test_write_dset (const char* file_name, const back_end_t backend) {
   // write numerical attribute in an empty file
   rc = trexio_write_nucleus_num(file, num);
   assert (rc == TREXIO_SUCCESS);
-  
+
   // write numerical dataset in a file
   rc = trexio_write_nucleus_coord(file, coord);
   assert (rc == TREXIO_SUCCESS);
@@ -144,5 +144,3 @@ int main(void) {
 
   return 0;
 }
-
-

tests/io_dset_int_hdf5.c

@@ -27,7 +27,7 @@ static int test_write_dset (const char* file_name, const back_end_t backend) {
   // write numerical attribute in an empty file
   rc = trexio_write_basis_shell_num(file, num);
   assert (rc == TREXIO_SUCCESS);
-  
+
   // write numerical (integer) dataset in a file
   rc = trexio_write_basis_nucleus_index(file, nucl_index);
   assert (rc == TREXIO_SUCCESS);
@@ -51,10 +51,18 @@ static int test_has_dset (const char* file_name, const back_end_t backend) {
 
 /*================= START OF TEST ==================*/
 
-  // open file 
+  // open file
   file = trexio_open(file_name, 'r', backend, &rc);
   assert (file != NULL);
 
+  // check that the group exists
+  rc = trexio_has_basis(file);
+  assert(rc==TREXIO_SUCCESS);
+
+  // check that the group does not exist
+  rc = trexio_has_mo(file);
+  assert(rc==TREXIO_HAS_NOT);
+
   // check that the previously written dataset exists
   rc = trexio_has_basis_nucleus_index(file);
   assert (rc == TREXIO_SUCCESS);
@@ -130,5 +138,3 @@ int main(void) {
 
   return 0;
 }
-
-

tests/io_dset_int_text.c

@@ -5,7 +5,7 @@
 
 #define TEST_BACKEND 	TREXIO_TEXT
 #define TREXIO_FILE 	"test_dset_i.dir"
-#define RM_COMMAND 	"rm -rf " TREXIO_FILE
+#define RM_COMMAND 	"rm -f -- " TREXIO_FILE "/*.txt " TREXIO_FILE "/*.txt.size " TREXIO_FILE "/.lock && rm -fd -- " TREXIO_FILE
 
 static int test_write_dset (const char* file_name, const back_end_t backend) {
 
@@ -27,7 +27,7 @@ static int test_write_dset (const char* file_name, const back_end_t backend) {
   // write numerical attribute in an empty file
   rc = trexio_write_basis_shell_num(file, num);
   assert (rc == TREXIO_SUCCESS);
-  
+
   // write numerical (integer) dataset in a file
   rc = trexio_write_basis_nucleus_index(file, nucl_index);
   assert (rc == TREXIO_SUCCESS);
@@ -51,10 +51,18 @@ static int test_has_dset (const char* file_name, const back_end_t backend) {
 
 /*================= START OF TEST ==================*/
 
-  // open file 
+  // open file
   file = trexio_open(file_name, 'r', backend, &rc);
   assert (file != NULL);
 
+  // check that the group exists
+  rc = trexio_has_basis(file);
+  assert(rc==TREXIO_SUCCESS);
+
+  // check that the group does not exist
+  rc = trexio_has_mo(file);
+  assert(rc==TREXIO_HAS_NOT);
+
   // check that the previously written dataset exists
   rc = trexio_has_basis_nucleus_index(file);
   assert (rc == TREXIO_SUCCESS);
@@ -130,5 +138,3 @@ int main(void) {
 
   return 0;
 }
-
-

tests/io_dset_sparse_hdf5.c

@@ -86,6 +86,14 @@ static int test_has_dset_sparse (const char* file_name, const back_end_t backend
   assert (file != NULL);
   assert (rc == TREXIO_SUCCESS);
 
+  // check that the group exists
+  rc = trexio_has_mo_2e_int(file);
+  assert(rc==TREXIO_SUCCESS);
+
+  // check that the group does not exist
+  rc = trexio_has_rdm(file);
+  assert(rc==TREXIO_HAS_NOT);
+
   // first check that mo_2e_int_eri_lr (we only write non-lr component in this unit test)
   rc = trexio_has_mo_2e_int_eri_lr(file);
   assert(rc==TREXIO_HAS_NOT);
@@ -147,7 +155,7 @@ static int test_read_dset_sparse (const char* file_name, const back_end_t backen
   assert(index_read[4*offset_data_read] == 4 * (int32_t) (offset_file_read-offset));
 
   // now attempt to read so that one encounters end of file during reading (i.e. offset_file_read + chunk_read > size_max)
-  offset_file_read = 97;
+  offset_file_read = 97L;
   offset_data_read = 1;
   int64_t eof_read_size_check = SIZE - offset_file_read; // if offset_file_read=97 => only 3 integrals will be read out of total of 100
 
@@ -159,11 +167,6 @@ static int test_read_dset_sparse (const char* file_name, const back_end_t backen
   assert(chunk_read == eof_read_size_check);
   assert(index_read[4*size_r-1] == 0);
   assert(index_read[4*offset_data_read] == 4 * (int32_t) (offset_file_read-offset));
-  /*
-  for(int i=0; i<size_r; ++i){
-    printf("%d %lf\n", index_read[4*i], value_read[i]);
-  }
-  */
 
   // close current session
   rc = trexio_close(file);

tests/io_dset_sparse_text.c

@@ -6,7 +6,7 @@
 
 #define TEST_BACKEND  TREXIO_TEXT
 #define TREXIO_FILE   "test_dset_sparse.dir"
-#define RM_COMMAND    "rm -rf " TREXIO_FILE
+#define RM_COMMAND    "rm -f -- " TREXIO_FILE "/*.txt " TREXIO_FILE "/*.txt.size " TREXIO_FILE "/.lock && rm -fd -- " TREXIO_FILE
 #define SIZE          100
 #define N_CHUNKS      5
 
@@ -86,6 +86,14 @@ static int test_has_dset_sparse (const char* file_name, const back_end_t backend
   assert (file != NULL);
   assert (rc == TREXIO_SUCCESS);
 
+  // check that the group exists
+  rc = trexio_has_mo_2e_int(file);
+  assert(rc==TREXIO_SUCCESS);
+
+  // check that the group does not exist
+  rc = trexio_has_rdm(file);
+  assert(rc==TREXIO_HAS_NOT);
+
   // first check that mo_2e_int_eri_lr (we only write non-lr component in this unit test)
   rc = trexio_has_mo_2e_int_eri_lr(file);
   assert(rc==TREXIO_HAS_NOT);

tests/io_dset_str_text.c

@@ -6,7 +6,7 @@
 
 #define TEST_BACKEND 	TREXIO_TEXT
 #define TREXIO_FILE 	"test_dset_s.dir"
-#define RM_COMMAND 	"rm -rf " TREXIO_FILE
+#define RM_COMMAND 	"rm -f -- " TREXIO_FILE "/*.txt " TREXIO_FILE "/*.txt.size " TREXIO_FILE "/.lock && rm -fd -- " TREXIO_FILE
 
 static int test_write_dset_str (const char* file_name, const back_end_t backend) {
 
@@ -39,7 +39,7 @@ static int test_write_dset_str (const char* file_name, const back_end_t backend)
   // write numerical attribute in an empty file
   rc = trexio_write_nucleus_num(file, num);
   assert (rc == TREXIO_SUCCESS);
-  
+
   // write dataset of string in the file (including FAKE statements)
   int max_str_len = 16;
   rc = trexio_write_nucleus_label(file, labels, max_str_len);
@@ -153,5 +153,3 @@ int main(void) {
 
   return 0;
 }
-
-

tests/io_num_text.c

@@ -5,7 +5,7 @@
 
 #define TEST_BACKEND 	TREXIO_TEXT
 #define TREXIO_FILE 	"test_num.dir"
-#define RM_COMMAND 	"rm -rf " TREXIO_FILE
+#define RM_COMMAND 	"rm -f -- " TREXIO_FILE "/*.txt " TREXIO_FILE "/*.txt.size " TREXIO_FILE "/.lock && rm -fd -- " TREXIO_FILE
 
 static int test_write_num (const char* file_name, const back_end_t backend) {
 

tests/io_safe_dset_float_text.c

@@ -6,7 +6,7 @@
 
 #define TEST_BACKEND 	TREXIO_TEXT
 #define TREXIO_FILE 	"test_safe_dset_f.dir"
-#define RM_COMMAND 	"rm -rf " TREXIO_FILE
+#define RM_COMMAND 	"rm -f -- " TREXIO_FILE "/*.txt " TREXIO_FILE "/*.txt.size " TREXIO_FILE "/.lock && rm -fd -- " TREXIO_FILE
 
 static int test_write_dset (const char* file_name, const back_end_t backend) {
 
@@ -41,7 +41,7 @@ static int test_write_dset (const char* file_name, const back_end_t backend) {
   // write numerical attribute in an empty file
   rc = trexio_write_nucleus_num(file, num);
   assert (rc == TREXIO_SUCCESS);
-  
+
   /* write numerical dataset with an unsafe dimension
    * this should return TREXIO_UNSAFE_ARRAY_DIM indicating
    * that access beyong allocated memory is likely to occur */
@@ -161,5 +161,3 @@ int main(void) {
 
   return 0;
 }
-
-

tests/io_str_text.c

@@ -6,7 +6,7 @@
 
 #define TEST_BACKEND 	TREXIO_TEXT
 #define TREXIO_FILE 	"test_str.dir"
-#define RM_COMMAND 	"rm -rf " TREXIO_FILE
+#define RM_COMMAND 	"rm -f -- " TREXIO_FILE "/*.txt " TREXIO_FILE "/*.txt.size " TREXIO_FILE "/.lock && rm -fd -- " TREXIO_FILE
 
 static int test_write_str (const char* file_name, const back_end_t backend) {
 
@@ -129,5 +129,3 @@ int main(void) {
 
   return 0;
 }
-
-

tests/open_text.c

@@ -6,7 +6,7 @@
 #define TEST_BACKEND 	TREXIO_TEXT
 #define TREXIO_FILE 	"test_open.dir"
 #define TREXIO_VOID 	"non_existing_" TREXIO_FILE
-#define RM_COMMAND 	"rm -rf " TREXIO_FILE
+#define RM_COMMAND 	"rm -f -- " TREXIO_FILE "/*.txt " TREXIO_FILE "/*.txt.size " TREXIO_FILE "/.lock && rm -fd -- " TREXIO_FILE
 
 
 static int test_open_w (const char* file_name, const back_end_t backend) {

tests/overwrite_all_text.c

@@ -6,7 +6,7 @@
 
 #define TEST_BACKEND 	TREXIO_TEXT
 #define TREXIO_FILE 	"test_over.dir"
-#define RM_COMMAND 	"rm -rf " TREXIO_FILE
+#define RM_COMMAND 	"rm -f -- " TREXIO_FILE "/*.txt " TREXIO_FILE "/*.txt.size " TREXIO_FILE "/.lock && rm -fd -- " TREXIO_FILE
 
 static int test_write (const char* file_name, const back_end_t backend) {
 

tests/pre_close.c

@@ -5,8 +5,8 @@
 #include <stdint.h>
 
 #define TEST_BACKEND  TREXIO_TEXT
-#define TREXIO_FILE   "test_dset_sparse.dir"
+#define TREXIO_FILE 	"test_pre_close.dir"
-#define RM_COMMAND    "rm -rf " TREXIO_FILE
+#define RM_COMMAND 	"rm -f -- " TREXIO_FILE "/*.txt " TREXIO_FILE "/*.txt.size " TREXIO_FILE "/.lock && rm -fd -- " TREXIO_FILE
 
 static int test_pre_close_1 (const char* file_name, const back_end_t backend)
 {

tests/test_f.f90

@@ -6,20 +6,20 @@ program test_trexio
   integer :: rc
   logical :: have_hdf5
 
-  print *      , "============================================"
+  print'(a)'   , "============================================"
   print'(a,a)' , "         TREXIO VERSION STRING : ", TREXIO_PACKAGE_VERSION
   print'(a,i3)', "         TREXIO MAJOR VERSION  : ", TREXIO_VERSION_MAJOR
   print'(a,i3)', "         TREXIO MINOR VERSION  : ", TREXIO_VERSION_MINOR
-  print *      , "============================================"
+  print'(a)'   , "============================================"
 
   rc = trexio_info()
 
-  call system('rm -rf -- test_write_f.dir')
+  call system('rm -f -- test_write_f.dir/*.txt test_write_f.dir/*.txt.size test_write_f.dir/.lock && rm -fd -- test_write_f.dir')
   print *, 'call test_write(''test_write_f.dir'', TREXIO_TEXT)'
   call test_write('test_write_f.dir', TREXIO_TEXT)
   print *, 'call test_read(''test_write_f.dir'', TREXIO_TEXT)'
   call test_read('test_write_f.dir', TREXIO_TEXT)
-  call system('rm -rf -- test_write_f.dir')
+  call system('rm -f -- test_write_f.dir/*.txt test_write_f.dir/*.txt.size test_write_f.dir/.lock && rm -fd -- test_write_f.dir')
 
   call test_read_void('test_write_f.dir', TREXIO_TEXT)
 
@@ -55,7 +55,7 @@ subroutine test_write(file_name, back_end)
 
   integer(trexio_exit_code) :: rc = 1
 
-  integer :: num, basis_shell_num
+  integer :: nucleus_num, mo_num, ao_num, basis_shell_num
 
   integer :: basis_nucleus_index(24)
   double precision :: charge(12)
@@ -63,25 +63,42 @@ subroutine test_write(file_name, back_end)
 
   character(len=:), allocatable :: sym_str
   character(len=:), allocatable :: label(:)
+  double precision, allocatable :: energy(:)
+  integer         , allocatable :: spin(:)
 
   ! sparse data
-  integer(4) :: index_sparse_mo_2e_int_eri(4,100)
+  integer(4) :: index_sparse_ao_2e_int_eri(4,100)
-  double precision :: value_sparse_mo_2e_int_eri(100)
+  double precision :: value_sparse_ao_2e_int_eri(100)
 
-  integer :: i, n_buffers = 5
+  ! determinants
-  integer(8) :: buf_size, offset
+  integer*8 :: det_list(6, 50)
-  buf_size = 100/n_buffers
+  integer*8 :: det_num
+  integer   :: int_num
 
+  integer :: i, j, n_buffers = 5
+  integer(8) :: buf_size_sparse, buf_size_det, offset
+
+  buf_size_sparse = 100/n_buffers
+  buf_size_det    = 50/n_buffers
+
+  ! fill sparse indices and values
   do i = 1, 100
-    index_sparse_mo_2e_int_eri(1,i) = 4*i   - 3
+    index_sparse_ao_2e_int_eri(1,i) = 4*i   - 3
-    index_sparse_mo_2e_int_eri(2,i) = 4*i+1 - 3
+    index_sparse_ao_2e_int_eri(2,i) = 4*i+1 - 3
-    index_sparse_mo_2e_int_eri(3,i) = 4*i+2 - 3
+    index_sparse_ao_2e_int_eri(3,i) = 4*i+2 - 3
-    index_sparse_mo_2e_int_eri(4,i) = 4*i+3 - 3
+    index_sparse_ao_2e_int_eri(4,i) = 4*i+3 - 3
-    value_sparse_mo_2e_int_eri(i) = 3.14 + float(i)
+    value_sparse_ao_2e_int_eri(i) = 3.14 + float(i)
+  enddo
+
+  ! fill determinant list
+  do i = 1, 50
+    do j = 1, 6
+      det_list(j,i) = 6*i+(j-1) - 5
+    enddo
   enddo
 
   ! parameters to be written
-  num = 12
+  nucleus_num = 12
   charge = (/ 6., 6., 6., 6., 6., 6., 1., 1., 1., 1., 1., 1.  /)
   coord  = reshape( (/ 0.00000000d0,  1.39250319d0 ,  0.00000000d0 , &
                       -1.20594314d0,  0.69625160d0 ,  0.00000000d0 , &
@@ -97,6 +114,10 @@ subroutine test_write(file_name, back_end)
                        0.00000000d0,  2.47304151d0 ,  0.00000000d0 /), &
                        shape(coord) )
 
+  ! the first dimension of det_list (6) corresponds to mo_num=150; adapt the former if the latter is changed
+  mo_num = 150
+  ao_num = 1000
+
   basis_shell_num = 24
   basis_nucleus_index = (/ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 /)
 
@@ -118,10 +139,19 @@ subroutine test_write(file_name, back_end)
   rc = trexio_has_nucleus_charge(trex_file)
   call trexio_assert(rc, TREXIO_HAS_NOT, 'SUCCESS HAS NOT 2')
 
-  rc = trexio_has_mo_2e_int_eri(trex_file)
+  rc = trexio_has_ao_2e_int_eri(trex_file)
   call trexio_assert(rc, TREXIO_HAS_NOT, 'SUCCESS HAS NOT 3')
 
-  rc = trexio_write_nucleus_num(trex_file, num)
+  rc = trexio_has_determinant_list(trex_file)
+  call trexio_assert(rc, TREXIO_HAS_NOT, 'SUCCESS HAS NOT 4')
+
+  rc = trexio_has_nucleus(trex_file)
+  call trexio_assert(rc, TREXIO_HAS_NOT, 'SUCCESS HAS NOT 5')
+
+  rc = trexio_has_ao_2e_int(trex_file)
+  call trexio_assert(rc, TREXIO_HAS_NOT, 'SUCCESS HAS NOT 6')
+
+  rc = trexio_write_nucleus_num(trex_file, nucleus_num)
   call trexio_assert(rc, TREXIO_SUCCESS, 'SUCCESS WRITE NUM')
 
   rc = trexio_write_nucleus_charge(trex_file, charge)
@@ -144,19 +174,50 @@ subroutine test_write(file_name, back_end)
   rc = trexio_write_basis_nucleus_index(trex_file, basis_nucleus_index)
   call trexio_assert(rc, TREXIO_SUCCESS, 'SUCCESS WRITE INDEX')
 
-  ! write mo_num which will be used to determine the optimal size of int indices
+  ! write ao_num which will be used to determine the optimal size of int indices
+  if (trexio_has_ao_num(trex_file) == TREXIO_HAS_NOT) then
+    rc = trexio_write_ao_num(trex_file, ao_num)
+    call trexio_assert(rc, TREXIO_SUCCESS, 'SUCCESS WRITE AO NUM')
+  endif
+  ! write mo_num which will be used to determine the optimal size of the determinants bit fields
   if (trexio_has_mo_num(trex_file) == TREXIO_HAS_NOT) then
-    rc = trexio_write_mo_num(trex_file, 1000)
+    rc = trexio_write_mo_num(trex_file, mo_num)
     call trexio_assert(rc, TREXIO_SUCCESS, 'SUCCESS WRITE MO NUM')
   endif
 
+  allocate(energy(mo_num))
+  do i=1,mo_num
+    energy(i) = dble(i)-100.d0
+  enddo
+  rc = trexio_write_mo_energy(trex_file, energy)
+  call trexio_assert(rc, TREXIO_SUCCESS, 'SUCCESS WRITE ENERGY')
+  deallocate(energy)
+
+  allocate(spin(mo_num))
+  spin(:) = 0
+  do i=mo_num/2+1,mo_num
+    spin(i) = 1
+  enddo
+  rc = trexio_write_mo_spin(trex_file, spin)
+  call trexio_assert(rc, TREXIO_SUCCESS, 'SUCCESS WRITE SPIN')
+  deallocate(spin)
+
+
   offset = 0
   do i = 1,n_buffers
-    rc = trexio_write_mo_2e_int_eri(trex_file, offset, buf_size, &
+    rc = trexio_write_ao_2e_int_eri(trex_file, offset, buf_size_sparse, &
-	                            index_sparse_mo_2e_int_eri(1,offset+1), &
+                                      index_sparse_ao_2e_int_eri(1,offset+1), &
-				    value_sparse_mo_2e_int_eri(offset+1))
+                                            value_sparse_ao_2e_int_eri(offset+1))
     call trexio_assert(rc, TREXIO_SUCCESS, 'SUCCESS WRITE SPARSE')
-    offset = offset + buf_size
+    offset = offset + buf_size_sparse
+  enddo
+
+  offset = 0
+  do i = 1,n_buffers
+    rc = trexio_write_determinant_list(trex_file, offset, buf_size_det, &
+                                         det_list(1,offset+1))
+    call trexio_assert(rc, TREXIO_SUCCESS, 'SUCCESS WRITE DET LIST')
+    offset = offset + buf_size_det
   enddo
 
   rc = trexio_has_nucleus_num(trex_file)
@@ -165,9 +226,18 @@ subroutine test_write(file_name, back_end)
   rc = trexio_has_nucleus_coord(trex_file)
   call trexio_assert(rc, TREXIO_SUCCESS, 'SUCCESS HAS 2')
 
-  rc = trexio_has_mo_2e_int_eri(trex_file)
+  rc = trexio_has_ao_2e_int_eri(trex_file)
   call trexio_assert(rc, TREXIO_SUCCESS, 'SUCCESS HAS 3')
 
+  rc = trexio_has_determinant_list(trex_file)
+  call trexio_assert(rc, TREXIO_SUCCESS, 'SUCCESS HAS 4')
+
+  rc = trexio_has_nucleus(trex_file)
+  call trexio_assert(rc, TREXIO_SUCCESS, 'SUCCESS HAS 5')
+
+  rc = trexio_has_ao_2e_int(trex_file)
+  call trexio_assert(rc, TREXIO_SUCCESS, 'SUCCESS HAS 6')
+
   rc = trexio_close(trex_file)
   call trexio_assert(rc, TREXIO_SUCCESS, 'SUCCESS CLOSE')
 
@@ -201,10 +271,13 @@ subroutine test_read(file_name, back_end)
   character(len=4) :: label(12) ! also works with allocatable arrays
 
   character(len=32) :: sym_str
+  integer           :: mo_num
+  double precision, allocatable :: energy(:)
+  integer         , allocatable :: spin(:)
 
   ! sparse data
-  integer(4) :: index_sparse_mo_2e_int_eri(4,20)
+  integer(4) :: index_sparse_ao_2e_int_eri(4,20)
-  double precision :: value_sparse_mo_2e_int_eri(20)
+  double precision :: value_sparse_ao_2e_int_eri(20)
   integer(8) :: read_buf_size = 10
   integer(8) :: read_buf_size_save = 10
   integer(8) :: offset_read = 40
@@ -213,13 +286,31 @@ subroutine test_read(file_name, back_end)
   integer(8) :: offset_data_eof = 1
   integer(8) :: size_toread = 0
 
+  ! determinant data
+  integer*8 :: det_list(6,50)
+  integer*8 :: det_list_check(3)
+  integer*8 :: read_buf_det_size = 20
+  integer*8 :: offset_det_read = 10
+  integer*8 :: offset_det_data_read = 5
+  integer*8 :: determinant_num
+  integer   :: int_num
+
+  ! orbital lists
+  integer*4 :: orb_list_up(150)
+  integer*4 :: orb_list_dn(150)
+  integer*4 :: occ_num_up, occ_num_dn
+
   character*(128) :: str
 
   num = 12
   basis_shell_num = 24
 
-  index_sparse_mo_2e_int_eri = 0
+  index_sparse_ao_2e_int_eri = 0
-  value_sparse_mo_2e_int_eri = 0.0d0
+  value_sparse_ao_2e_int_eri = 0.0d0
+
+  det_list = 0_8
+  orb_list_up = 0
+  orb_list_dn = 0
 
 ! ================= START OF TEST ===================== !
 
@@ -259,9 +350,11 @@ subroutine test_read(file_name, back_end)
   endif
 
 
-  rc = trexio_read_nucleus_label(trex_file, label, 2)
+  rc = trexio_read_nucleus_label(trex_file, label, 4)
   call trexio_assert(rc, TREXIO_SUCCESS)
-  if (trim(label(2)) == 'Na') then
+  if (trim(label(2)) == 'Na'   .and. &
+      trim(label(4)) == 'C 66' .and. &
+      trim(label(5)) == 'C')   then
     write(*,*) 'SUCCESS READ LABEL'
   else
     print *, 'FAILURE LABEL CHECK'
@@ -289,15 +382,15 @@ subroutine test_read(file_name, back_end)
   endif
 
 
-  rc = trexio_read_mo_2e_int_eri(trex_file, offset_read, read_buf_size, &
+  rc = trexio_read_ao_2e_int_eri(trex_file, offset_read, read_buf_size, &
-	                         index_sparse_mo_2e_int_eri(1, offset_data_read + 1), &
+                                 index_sparse_ao_2e_int_eri(1, offset_data_read + 1), &
-			         value_sparse_mo_2e_int_eri(offset_data_read + 1))
+                                 value_sparse_ao_2e_int_eri(offset_data_read + 1))
   !do  i = 1,20
-  !  write(*,*) index_sparse_mo_2e_int_eri(1,i)
+  !  write(*,*) index_sparse_ao_2e_int_eri(1,i)
   !enddo
   call trexio_assert(rc, TREXIO_SUCCESS)
-  if (index_sparse_mo_2e_int_eri(1, 1) == 0 .and. &
+  if (index_sparse_ao_2e_int_eri(1, 1) == 0 .and. &
-      index_sparse_mo_2e_int_eri(1, offset_data_read + 1) == offset_read*4 + 1) then
+      index_sparse_ao_2e_int_eri(1, offset_data_read + 1) == offset_read*4 + 1) then
     write(*,*) 'SUCCESS READ SPARSE DATA'
   else
     print *, 'FAILURE SPARSE DATA CHECK'
@@ -307,17 +400,17 @@ subroutine test_read(file_name, back_end)
 
   ! attempt to read reaching EOF: should return TREXIO_END and
   ! NOT increment the existing values in the buffer (only upd with what has been read)
-  rc = trexio_read_mo_2e_int_eri(trex_file, offset_eof, read_buf_size, &
+  rc = trexio_read_ao_2e_int_eri(trex_file, offset_eof, read_buf_size, &
-	                         index_sparse_mo_2e_int_eri(1, offset_data_eof + 1), &
+                             index_sparse_ao_2e_int_eri(1, offset_data_eof + 1), &
-			         value_sparse_mo_2e_int_eri(offset_data_eof + 1))
+                     value_sparse_ao_2e_int_eri(offset_data_eof + 1))
   !do  i = 1,20
-  !  write(*,*) index_sparse_mo_2e_int_eri(1,i)
+  !  write(*,*) index_sparse_ao_2e_int_eri(1,i)
   !enddo
   call trexio_assert(rc, TREXIO_END)
   if (read_buf_size == 3 .and. &
-      index_sparse_mo_2e_int_eri(1, 1) == 0 .and. &
+      index_sparse_ao_2e_int_eri(1, 1) == 0 .and. &
-      index_sparse_mo_2e_int_eri(1, offset_data_read + 1) == offset_read*4 + 1 .and. &
+      index_sparse_ao_2e_int_eri(1, offset_data_read + 1) == offset_read*4 + 1 .and. &
-      index_sparse_mo_2e_int_eri(1, offset_data_eof + 1) == offset_eof*4 + 1) then
+      index_sparse_ao_2e_int_eri(1, offset_data_eof + 1) == offset_eof*4 + 1) then
     write(*,*) 'SUCCESS READ SPARSE DATA EOF'
     read_buf_size = read_buf_size_save
   else
@@ -325,7 +418,8 @@ subroutine test_read(file_name, back_end)
     call exit(-1)
   endif
 
-  rc = trexio_read_mo_2e_int_eri_size(trex_file, size_toread)
+  ! read the size (number of integrals) of the sparse dataset
+  rc = trexio_read_ao_2e_int_eri_size(trex_file, size_toread)
   call trexio_assert(rc, TREXIO_SUCCESS)
   if (size_toread == 100) then
     write(*,*) 'SUCCESS READ SPARSE SIZE'
@@ -334,7 +428,99 @@ subroutine test_read(file_name, back_end)
     call exit(-1)
   endif
 
+  ! obtain a number of int64 bit fields per determinant
+  rc = trexio_get_int64_num(trex_file, int_num)
+  call trexio_assert(rc, TREXIO_SUCCESS)
+  if (int_num == 3) then
+    write(*,*) 'SUCCESS GET INT64_NUM'
+  else
+    print *, 'FAILURE DET INT64_NUM CHECK'
+    call exit(-1)
+  endif
 
+  ! read a chunk of determinants
+  rc = trexio_read_determinant_list(trex_file, offset_det_read, read_buf_det_size, &
+                                    det_list(1, offset_det_data_read + 1))
+  !do  i = 1,50
+  !  write(*,*) det_list(1,i)
+  !enddo
+  call trexio_assert(rc, TREXIO_SUCCESS)
+  if (det_list(1, 1) == 0 .and. &
+      det_list(1, offset_det_data_read + 1) == offset_det_read*6 + 1) then
+    write(*,*) 'SUCCESS READ DET LIST'
+  else
+    print *, 'FAILURE DET LIST CHECK'
+    call exit(-1)
+  endif
+
+  ! read the total number of stored determinants
+  rc = trexio_read_determinant_num_64(trex_file, determinant_num)
+  call trexio_assert(rc, TREXIO_SUCCESS)
+  if (determinant_num == 50_8) then
+    write(*,*) 'SUCCESS READ DET NUM'
+  else
+    print *, 'FAILURE DET NUM CHECK'
+    call exit(-1)
+  endif
+
+  ! convert one given determinant into lists of orbitals
+  rc = trexio_to_orbital_list_up_dn(3, det_list(:, offset_det_data_read+1), orb_list_up, orb_list_dn, occ_num_up, occ_num_dn)
+  !write(*,*) occ_num_up, occ_num_dn
+  ! Print occupied orbitals for an up-spin component of a given determinant
+  !write(*,*) orb_list_up(1:occ_num_up)
+  ! Print integers representanting a given determinant fully (up- and down-spin components)
+  !write(*,*) det_list(:, offset_det_data_read+1)
+  ! Print binary representation of the first integer bit field of a given determinant
+  !write(*,'(B64.64)') det_list(1, offset_det_data_read+1)
+  call trexio_assert(rc, TREXIO_SUCCESS)
+  if (occ_num_up == 16 .and. occ_num_dn == 5) then
+    write(*,*) 'SUCCESS CONVERT DET LIST'
+  else
+    print *, 'FAILURE DET CONVERT CHECK'
+    call exit(-1)
+  endif
+
+  ! convert one orbital list into a bitfield determinant representation
+  rc = trexio_to_bitfield_list(orb_list_up, occ_num_up, det_list_check, 3)
+  !write(*,*) occ_num_up, occ_num_dn
+  ! Print occupied orbitals for an up-spin component of a given determinant
+  !write(*,*) orb_list_up(1:occ_num_up)
+  ! Print integers representanting a given determinant fully (up- and down-spin components)
+  !write(*,*) det_list(1:3, offset_det_data_read+1)
+  !write(*,*) det_list_check(1:3)
+  ! Print binary representation of the first integer bit field of a given determinant
+  !write(*,'(B64.64)') det_list(1, offset_det_data_read+1)
+  call trexio_assert(rc, TREXIO_SUCCESS)
+  if (det_list_check(1) == det_list(1, offset_det_data_read+1) .and. &
+      det_list_check(2) == det_list(2, offset_det_data_read+1) .and. &
+      det_list_check(3) == det_list(3, offset_det_data_read+1)) then
+    write(*,*) 'SUCCESS CONVERT ORB LIST'
+  else
+    print *, 'FAILURE ORB CONVERT CHECK'
+    call exit(-1)
+  endif
+
+  rc = trexio_read_mo_num(trex_file, mo_num)
+  call trexio_assert(rc, TREXIO_SUCCESS)
+
+  allocate(spin(mo_num), energy(mo_num))
+  rc = trexio_read_mo_energy(trex_file, energy)
+  call trexio_assert(rc, TREXIO_SUCCESS)
+
+  if (energy(10) /= -90.d0) then
+     print *, 'Failure to read MO energy: ', energy(10)
+     call exit(-1)
+  end if
+
+  rc = trexio_read_mo_spin(trex_file, spin)
+  call trexio_assert(rc, TREXIO_SUCCESS)
+
+  if (sum(spin) /= mo_num/2) then
+     print *, 'Failure to read MO spin', mo_num, sum(spin)
+     call exit(-1)
+  end if
+
+  ! close the file
   rc = trexio_close(trex_file)
   call trexio_assert(rc, TREXIO_SUCCESS)
 
@@ -352,7 +538,7 @@ subroutine test_read_void(file_name, back_end)
   character*(*), intent(in) :: file_name
   integer, intent(in) :: back_end
 
-  integer(8) :: trex_file
+  integer(trexio_t) :: trex_file
   integer :: rc = 1
   character(128) :: str
 
@@ -365,7 +551,7 @@ subroutine test_read_void(file_name, back_end)
   call trexio_assert(rc, TREXIO_OPEN_ERROR)
 
   call trexio_string_of_error(rc, str)
-  print *, trim(str)
+  print *, 'Test error message: ', trim(str)
 
 ! ================= END OF TEST ===================== !
 

tools/generator.py

@@ -12,12 +12,12 @@ detailed_nums = get_detailed_num_dict(trex_config)
 detailed_strs = get_detailed_str_dict(trex_config)
 # helper dictionaries that contain names of groups, nums or dsets as keys
 dsets = get_dset_dict(trex_config)
-detailed_dsets_nostr, detailed_dsets_str, detailed_dsets_sparse = split_dset_dict_detailed(dsets)
+detailed_dsets_nostr, detailed_dsets_str, detailed_dsets_sparse, detailed_dsets_buf = split_dset_dict_detailed(dsets)
 detailed_dsets = detailed_dsets_nostr.copy()
 detailed_dsets.update(detailed_dsets_str)
 # build a big dictionary with all pre-processed data
 detailed_all = {
-    'datasets' : dict(detailed_dsets_nostr, **detailed_dsets_str, **detailed_dsets_sparse),
+    'datasets' : dict(detailed_dsets_nostr, **detailed_dsets_str, **detailed_dsets_sparse, **detailed_dsets_buf),
     'groups'   : group_dict,
     'numbers'  : detailed_nums,
     'strings'  : detailed_strs
@@ -62,10 +62,14 @@ for fname in files_todo['dset_str']:
 for fname in files_todo['dset_sparse']:
     recursive_populate_file(fname, template_paths, detailed_dsets_sparse)
 
+# populate has/read/write_buffered functions with recursive scheme
+for fname in files_todo['buffered']:
+    recursive_populate_file(fname, template_paths, detailed_dsets_buf)
+
 # populate group-related functions with mixed scheme
 for fname in files_todo['group']:
     # recursive scheme for delete_group functions
-    if 'delete' in fname:
+    if 'delete' in fname or 'has' in fname:
         recursive_populate_file(fname, template_paths, group_dict)
     # mixed (iterative+recursive) scheme [text backend]
     else:

tools/generator_tools.py

@@ -37,8 +37,11 @@ def get_files_todo(source_files: dict) -> dict:
         all_files += source_files[key]
 
     files_todo = {}
-    files_todo['all'] = [f for f in all_files if 'read' in f or 'write' in f or 'has' in f or 'flush' in f or 'free' in f or 'hrw' in f or 'delete' in f]
+    files_todo['all'] = [
-    for key in ['dset_data', 'dset_str', 'dset_sparse', 'attr_num', 'attr_str', 'group']:
+        f for f in all_files
+        if 'read' in f or 'write' in f or 'has' in f or 'flush' in f or 'free' in f or 'hrw' in f or 'delete' in f
+        ]
+    for key in ['dset_data', 'dset_str', 'dset_sparse', 'attr_num', 'attr_str', 'group', 'buffered']:
         files_todo[key] = list(filter(lambda x: key in x, files_todo['all']))
 
     files_todo['group'].append('struct_text_group_dset.h')
@@ -105,17 +108,23 @@ def recursive_populate_file(fname: str, paths: dict, detailed_source: dict) -> N
     triggers = ['group_dset_dtype', 'group_dset_py_dtype', 'group_dset_h5_dtype', 'default_prec', 'is_index',
                 'group_dset_f_dtype_default', 'group_dset_f_dtype_double', 'group_dset_f_dtype_single',
                 'group_dset_dtype_default', 'group_dset_dtype_double', 'group_dset_dtype_single',
-                'group_dset_rank', 'group_dset_dim_list', 'group_dset_f_dims',
+                'group_dset_rank', 'group_dset_unique_rank', 'group_dset_dim_list', 'group_dset_f_dims',
                 'group_num_f_dtype_default', 'group_num_f_dtype_double', 'group_num_f_dtype_single',
                 'group_num_dtype_default', 'group_num_dtype_double', 'group_num_dtype_single',
-                'group_num_h5_dtype', 'group_num_py_dtype',
+                'group_num_h5_dtype', 'group_num_py_dtype', 'group_dset_format_scanf', 'group_dset_format_printf',
-                'group_dset_format_scanf', 'group_dset_format_printf', 'group_dset_sparse_dim',
                 'group_dset_sparse_indices_printf', 'group_dset_sparse_indices_scanf',
                 'sparse_format_printf_8', 'sparse_format_printf_16', 'sparse_format_printf_32',
                 'sparse_line_length_8', 'sparse_line_length_16', 'sparse_line_length_32',
                 'group_dset', 'group_num', 'group_str', 'group']
 
     for item in detailed_source.keys():
+
+        # special case to exclude write functions for readonly dimensions (like determinant_num) from the public API
+        if 'write' in fname and 'front' in fname and ('.f90' in fname or '.py' in fname):
+            if 'trex_json_int_type' in detailed_source[item].keys():
+                if 'readonly' in detailed_source[item]['trex_json_int_type']:
+                    continue
+
         with open(join(templ_path,fname), 'r') as f_in :
             with open(join(templ_path,fname_new), 'a') as f_out :
                 num_written = []
@@ -137,14 +146,27 @@ def recursive_populate_file(fname: str, paths: dict, detailed_source: dict) -> N
                         continue
                     # special case to uncomment check for positive dimensioning variables in templates
                     elif 'uncommented by the generator for dimensioning' in line:
-                        # only uncomment and write the line if `num` is in the name
+                        # only uncomment and write the line if `dim` is in the name
                         if 'dim' in detailed_source[item]['trex_json_int_type']:
                             templine = line.replace('//', '')
                             f_out.write(templine)
+                    # special case to get the max dimension of sparse datasets with different dimensions
+                    elif 'trexio_read_$group_dset_unique_dim$_64' in line:
+                        for i in range(int(detailed_source[item]['group_dset_unique_rank'])):
+                            templine = line.replace('$group_dset_unique_dim$', detailed_source[item]['unique_dims'][i]).replace('$dim_id$', str(i))
+                            f_out.write(templine)
                     # general case of recursive replacement of inline triggers
                     else:
                         populated_line = recursive_replace_line(line, triggers, detailed_source[item])
-                        f_out.write(populated_line)
+                        # special case to include some functions in the private header
+                        if 'trex_json_int_type' in detailed_source[item].keys():
+                            if 'readonly' in detailed_source[item]['trex_json_int_type'] and 'write' in line and 'front.h' in fname:
+                                with open(join(templ_path,'populated/private_pop_front.h'), 'a') as f_priv:
+                                    f_priv.write(populated_line)
+                            else:
+                                f_out.write(populated_line)
+                        else:
+                            f_out.write(populated_line)
 
                 f_out.write("\n")
 
@@ -214,7 +236,7 @@ def iterative_populate_file (filename: str, paths: dict, detailed_all: dict) ->
             for line in f_in :
                 id = check_triggers(line, triggers)
                 if id == 0:
-                    # special case for proper error handling when deallocting text groups
+                    # special case for proper error handling when deallocating text groups
                     error_handler = '  if (rc != TREXIO_SUCCESS) return rc;\n'
                     populated_line = iterative_replace_line(line, '$group$', detailed_all['groups'], add_line=error_handler)
                     f_out.write(populated_line)
@@ -477,7 +499,22 @@ def get_dtype_dict (dtype: str, target: str, rank = None, int_len_printf = None)
             f'group_{target}_format_scanf'    : 'lf',
             f'group_{target}_py_dtype'        : 'float'
         })
-    elif dtype in ['int', 'dim', 'index']:
+    elif 'buffered' in dtype:
+        dtype_dict.update({
+            'default_prec'                    : '64',
+            f'group_{target}_dtype'           : 'double',
+            f'group_{target}_h5_dtype'        : 'native_double',
+            f'group_{target}_f_dtype_default' : 'real(c_double)',
+            f'group_{target}_f_dtype_double'  : 'real(c_double)',
+            f'group_{target}_f_dtype_single'  : 'real(c_float)',
+            f'group_{target}_dtype_default'   : 'double',
+            f'group_{target}_dtype_double'    : 'double',
+            f'group_{target}_dtype_single'    : 'float',
+            f'group_{target}_format_printf'   : '24.16e',
+            f'group_{target}_format_scanf'    : 'lf',
+            f'group_{target}_py_dtype'        : 'float'
+        })
+    elif dtype in ['int', 'dim', 'dim readonly', 'index']:
         dtype_dict.update({
             'default_prec'                    : '32',
             f'group_{target}_dtype'           : 'int64_t',
@@ -517,7 +554,7 @@ def get_dtype_dict (dtype: str, target: str, rank = None, int_len_printf = None)
         group_dset_format_printf_16 = '"'
         group_dset_format_printf_32 = '"'
         group_dset_format_scanf  = ''
-        for i in range(rank):
+        for _ in range(rank):
             group_dset_format_printf_8  += item_printf_8
             group_dset_format_printf_16 += item_printf_16
             group_dset_format_printf_32 += item_printf_32
@@ -568,16 +605,17 @@ def get_detailed_num_dict (configuration: dict) -> dict:
                 tmp_num = f'{k1}_{k2}'
                 if not 'str' in v2[0]:
                     tmp_dict = {}
+
                     tmp_dict['group'] = k1
                     tmp_dict['group_num'] = tmp_num
-                    num_dict[tmp_num] = tmp_dict
-
                     tmp_dict.update(get_dtype_dict(v2[0], 'num'))
-                    if v2[0] in ['int', 'dim']:
+                    if v2[0] in ['int', 'dim', 'dim readonly']:
                         tmp_dict['trex_json_int_type'] = v2[0]
                     else:
                         tmp_dict['trex_json_int_type'] = ''
 
+                    num_dict[tmp_num] = tmp_dict
+
     return num_dict
 
 
@@ -638,17 +676,23 @@ def split_dset_dict_detailed (datasets: dict) -> tuple:
                     configuration (dict) : configuration from `trex.json`
 
             Returns:
-                    dset_numeric_dict, dset_string_dict (tuple) : dictionaries corresponding to all numeric- and string-based datasets, respectively.
+                    (tuple) : dictionaries corresponding to all types of datasets in trexio.
     """
     dset_numeric_dict = {}
-    dset_string_dict = {}
+    dset_string_dict  = {}
-    dset_sparse_dict = {}
+    dset_sparse_dict  = {}
+    dset_buffer_dict  = {}
     for k,v in datasets.items():
+
         # create a temp dictionary
         tmp_dict = {}
         rank = len(v[1])
         datatype = v[0]
 
+        # skip the data which has 'special' datatype (e.g. determinants for which the code is not templated)
+        if 'special' in datatype:
+            continue
+
         # define whether the dset is sparse
         is_sparse = False
         int_len_printf = {}
@@ -674,11 +718,18 @@ def split_dset_dict_detailed (datasets: dict) -> tuple:
         else:
             tmp_dict['is_index'] = 'false'
 
+        # add the list of dimensions
+        tmp_dict['dims'] = [dim.replace('.','_') for dim in v[1]]
+
+        # get a list of unique dimensions for sparse datasets
+        if is_sparse:
+            tmp_dict['unique_dims'] = list(set(tmp_dict['dims']))
+            tmp_dict['group_dset_unique_rank'] = str(len(tmp_dict['unique_dims']))
+
         # add the rank
         tmp_dict['rank'] = rank
         tmp_dict['group_dset_rank'] = str(rank)
-        # add the list of dimensions
+
-        tmp_dict['dims'] = [dim.replace('.','_') for dim in v[1]]
         # build a list of dimensions to be inserted in the dims array initialization, e.g. {ao_num, ao_num}
         dim_list = tmp_dict['dims'][0]
         if rank > 1:
@@ -695,8 +746,6 @@ def split_dset_dict_detailed (datasets: dict) -> tuple:
         tmp_dict['group_dset_f_dims'] = dim_f_list
 
         if is_sparse:
-            # store the max possible dim of the sparse dset (e.g. mo_num)
-            tmp_dict['group_dset_sparse_dim'] = tmp_dict['dims'][0]
             # build printf/scanf sequence and compute line length for n-index sparse quantity
             index_printf = f'*(index_sparse + {str(rank)}*i'
             index_scanf  = f'index_sparse + {str(rank)}*i'
@@ -731,12 +780,14 @@ def split_dset_dict_detailed (datasets: dict) -> tuple:
         # split datasets in numeric- and string- based
         if 'str' in datatype:
             dset_string_dict[k] = tmp_dict
+        elif 'buffered' in datatype:
+            dset_buffer_dict[k] = tmp_dict
         elif is_sparse:
             dset_sparse_dict[k] = tmp_dict
         else:
             dset_numeric_dict[k] = tmp_dict
 
-    return (dset_numeric_dict, dset_string_dict, dset_sparse_dict)
+    return (dset_numeric_dict, dset_string_dict, dset_sparse_dict, dset_buffer_dict)
 
 
 def check_dim_consistency(num: dict, dset: dict) -> None:
@@ -757,7 +808,10 @@ def check_dim_consistency(num: dict, dset: dict) -> None:
             if dim not in dim_tocheck:
                 dim_tocheck.append(dim)
 
-    num_onlyDim = [attr_name for attr_name, specs in num.items() if specs['trex_json_int_type']=='dim']
+    num_onlyDim = [
+        attr_name for attr_name, specs in num.items()
+        if 'dim' in specs['trex_json_int_type']
+        ]
 
     for dim in dim_tocheck:
         if not dim in num_onlyDim:

tools/trexio.scm

@@ -1,15 +1,15 @@
-(define-module (gnu packages trexio)
+(define-module (trexio)
   #:use-module (guix packages)
   #:use-module (gnu packages pkg-config)
   #:use-module (gnu packages glib)
   #:use-module (gnu packages gcc)
   #:use-module (gnu packages autotools)
-  #:use-module (gnu packages maths)
+  #:use-module (gnu packages maths)  ;; contains hdf5
   #:use-module (guix download)
   #:use-module (guix build-system gnu)
   #:use-module (guix licenses))
 
-(define-public trexio
+(define-public trexio-2.0
   (package
     (name "trexio")
     (version "2.0")
@@ -20,15 +20,48 @@
                                   ".tar.gz"))
               (sha256
                (base32
+		;; the hash below is produced by guix download <url>
 		"1d2cn4w2r9gfid5b9wrq9q290kqdnbjdmvli76s1i5r58kdg5vkf"
                 ))))
     (build-system gnu-build-system)
     (arguments '(#:configure-flags '("--enable-silent-rules")))
-    (inputs `(("hdf5" ,hdf5-1.12) ("gfortran", gfortran)))
+    (inputs `(("hdf5" ,hdf5) ("gfortran", gfortran)))
-    (synopsis "TREX I/O lbrary: trexio package")
+    (synopsis "TREX I/O library")
-    (description "APIs in C and Fortran to exchange wavefunction data.
+    (description "The TREXIO library defines a standard format for storing wave functions, together with
-		  Supports HDF5 and TEXT back ends.")
+		 a C-compatible API such that it can be easily used in any programming language.")
     (home-page "https://trex-coe.github.io/trexio")
     (license bsd-3)))
 
+(define-public trexio-2.1
+  (package/inherit trexio-2.0
+    (version "2.1.0")
+    (source (origin
+              (method url-fetch)
+              (uri (string-append "https://github.com/TREX-CoE/trexio/releases/download/v" version
+				  "/trexio-" version
+                                  ".tar.gz"))
+              (sha256
+               (base32
+		;; the hash below is produced by guix download <url>
+		"10syfw4mq3wpp9anahmxnm7660bm1ya5xd9l5njai3xr8g4nca13"
+                ))))))
+
+(define-public trexio-2.2
+  (package/inherit trexio-2.0
+    (version "2.2.0")
+    (source (origin
+              (method url-fetch)
+              (uri (string-append "https://github.com/TREX-CoE/trexio/releases/download/v" version
+				  "/trexio-" version
+                                  ".tar.gz"))
+              (sha256
+               (base32
+		;; the hash below is produced by guix download <url>
+		"1n9n1gbk5hgvg73am991xrv7ap002rz719a3nvh8m8ff9x10qd76"
+                ))))))
+
+(define-public trexio
+  ;; Default version of TREXIO.
+  trexio-2.2)
+
 trexio

trex.org

@@ -22,6 +22,10 @@ variables cannot be negative. This additional constraint is required
 because ~dim~ attributes are used internally to allocate memory and to
 check array boundaries in the memory-safe API. Most of the times, the
 ~dim~ variables contain the ~num~ suffix.
+You may also encounter some ~dim readonly~ variables.
+It means that the value is automatically computed and written by the
+TREXIO library, thus it is read-only and cannot be (over)written by the
+user.
 
 In Fortran, arrays are 1-based and in most other languages the
 arrays are 0-based. Hence, we introduce the ~index~ type which is a
@@ -31,8 +35,16 @@ For sparse data structures such as electron replusion integrals,
 the data can be too large to fit in memory and the data needs to be
 fetched using multiple function calls to perform I/O on buffers.
 For more information on how to read/write sparse data structures, see
-the [[./examples.html][examples]].
+the [[./examples.html][examples]]. The ~sparse~ data representation implies the
+[[https://en.wikipedia.org/wiki/Sparse_matrix#Coordinate_list_(COO)][coordinate list]] representation, namely the user has to write a list
+of indices and values.
 
+For the Configuration Interfaction (CI) and Configuration State Function (CSF)
+groups, the ~buffered~ data type is introduced, which allows similar incremental
+I/O as for ~sparse~ data but without the need to write indices of the sparse values.
+
+For determinant lists (integer bit fields), the ~special~ attribute is present in the type.
+This means that the source code is not produced by the generator, but hand-written.
 
   #+begin_src python :tangle trex.json :exports none
 {
@@ -64,19 +76,19 @@ the [[./examples.html][examples]].
 
   #+CALL: json(data=metadata, title="metadata")
   #+RESULTS:
-  :RESULTS:
+  :results:
   #+begin_src python :tangle trex.json
       "metadata": {
-		 "code_num" : [ "dim", []                        ]
+                 "code_num" : [ "dim", []                        ]
-	,            "code" : [ "str", [ "metadata.code_num" ]   ]
+        ,            "code" : [ "str", [ "metadata.code_num" ]   ]
-	,      "author_num" : [ "dim", []                        ]
+        ,      "author_num" : [ "dim", []                        ]
-	,          "author" : [ "str", [ "metadata.author_num" ] ]
+        ,          "author" : [ "str", [ "metadata.author_num" ] ]
-	, "package_version" : [ "str", []                        ]
+        , "package_version" : [ "str", []                        ]
-	,     "description" : [ "str", []                        ]
+        ,     "description" : [ "str", []                        ]
-	,          "unsafe" : [ "int", []                        ]
+        ,          "unsafe" : [ "int", []                        ]
       } ,
   #+end_src
-  :END:
+  :end:
 
 * Electron (electron group)
 
@@ -191,20 +203,20 @@ If you encounter the aforementioned issue, please report it to our [[https://git
   #+CALL: json(data=ecp, title="ecp")
 
   #+RESULTS:
-  :RESULTS:
+  :results:
   #+begin_src python :tangle trex.json
       "ecp": {
-	  "max_ang_mom_plus_1" : [ "int"  , [ "nucleus.num" ] ]
+          "max_ang_mom_plus_1" : [ "int"  , [ "nucleus.num" ] ]
-	,             "z_core" : [ "int"  , [ "nucleus.num" ] ]
+        ,             "z_core" : [ "int"  , [ "nucleus.num" ] ]
-	,                "num" : [ "dim"  , []                ]
+        ,                "num" : [ "dim"  , []                ]
-	,            "ang_mom" : [ "int"  , [ "ecp.num" ]     ]
+        ,            "ang_mom" : [ "int"  , [ "ecp.num" ]     ]
-	,      "nucleus_index" : [ "index", [ "ecp.num" ]     ]
+        ,      "nucleus_index" : [ "index", [ "ecp.num" ]     ]
-	,           "exponent" : [ "float", [ "ecp.num" ]     ]
+        ,           "exponent" : [ "float", [ "ecp.num" ]     ]
-	,        "coefficient" : [ "float", [ "ecp.num" ]     ]
+        ,        "coefficient" : [ "float", [ "ecp.num" ]     ]
-	,              "power" : [ "int"  , [ "ecp.num" ]     ]
+        ,              "power" : [ "int"  , [ "ecp.num" ]     ]
       } ,
   #+end_src
-  :END:
+  :end:
 
 ** Example
 
@@ -310,6 +322,7 @@ power = [
   | ~nucleus_index~ | ~index~ | ~(basis.shell_num)~ | One-to-one correspondence between shells and atomic indices  |
   | ~shell_ang_mom~ | ~int~   | ~(basis.shell_num)~ | One-to-one correspondence between shells and angular momenta |
   | ~shell_factor~  | ~float~ | ~(basis.shell_num)~ | Normalization factor of each shell ($\mathcal{N}_s$)         |
+  | ~r_power~       | ~int~   | ~(basis.shell_num)~ | Power to which $r$ is raised ($n_s$)                         |
   | ~shell_index~   | ~index~ | ~(basis.prim_num)~  | One-to-one correspondence between primitives and shell index |
   | ~exponent~      | ~float~ | ~(basis.prim_num)~  | Exponents of the primitives ($\gamma_{ks}$)                  |
   | ~coefficient~   | ~float~ | ~(basis.prim_num)~  | Coefficients of the primitives ($a_{ks}$)                    |
@@ -318,22 +331,23 @@ power = [
   #+CALL: json(data=basis, title="basis")
 
   #+RESULTS:
-  :RESULTS:
+  :results:
   #+begin_src python :tangle trex.json
       "basis": {
-		   "type" : [ "str"  , []                    ]
+                   "type" : [ "str"  , []                    ]
-	,      "prim_num" : [ "dim"  , []                    ]
+        ,      "prim_num" : [ "dim"  , []                    ]
-	,     "shell_num" : [ "dim"  , []                    ]
+        ,     "shell_num" : [ "dim"  , []                    ]
-	, "nucleus_index" : [ "index", [ "basis.shell_num" ] ]
+        , "nucleus_index" : [ "index", [ "basis.shell_num" ] ]
-	, "shell_ang_mom" : [ "int"  , [ "basis.shell_num" ] ]
+        , "shell_ang_mom" : [ "int"  , [ "basis.shell_num" ] ]
-	,  "shell_factor" : [ "float", [ "basis.shell_num" ] ]
+        ,  "shell_factor" : [ "float", [ "basis.shell_num" ] ]
-	,   "shell_index" : [ "index", [ "basis.prim_num" ]  ]
+        ,       "r_power" : [ "int"  , [ "basis.shell_num" ] ]
-	,      "exponent" : [ "float", [ "basis.prim_num" ]  ]
+        ,   "shell_index" : [ "index", [ "basis.prim_num" ]  ]
-	,   "coefficient" : [ "float", [ "basis.prim_num" ]  ]
+        ,      "exponent" : [ "float", [ "basis.prim_num" ]  ]
-	,   "prim_factor" : [ "float", [ "basis.prim_num" ]  ]
+        ,   "coefficient" : [ "float", [ "basis.prim_num" ]  ]
+        ,   "prim_factor" : [ "float", [ "basis.prim_num" ]  ]
       } ,
   #+end_src
-  :END:
+  :end:
 
 ** Example
 
@@ -464,16 +478,16 @@ prim_factor =
   #+CALL: json(data=ao, title="ao")
 
   #+RESULTS:
-  :RESULTS:
+  :results:
   #+begin_src python :tangle trex.json
       "ao": {
-	      "cartesian" : [ "int"  , []           ]
+              "cartesian" : [ "int"  , []           ]
-	,           "num" : [ "dim"  , []           ]
+        ,           "num" : [ "dim"  , []           ]
-	,         "shell" : [ "index", [ "ao.num" ] ]
+        ,         "shell" : [ "index", [ "ao.num" ] ]
-	, "normalization" : [ "float", [ "ao.num" ] ]
+        , "normalization" : [ "float", [ "ao.num" ] ]
       } ,
   #+end_src
-  :END:
+  :end:
 
 ** One-electron integrals (~ao_1e_int~ group)
    :PROPERTIES:
@@ -492,13 +506,18 @@ prim_factor =
    over atomic orbitals.
 
    #+NAME: ao_1e_int
-  | Variable           | Type    | Dimensions         | Description                                            |
+  | Variable              | Type    | Dimensions         | Description                                                                       |
-  |--------------------+---------+--------------------+--------------------------------------------------------|
+  |-----------------------+---------+--------------------+-----------------------------------------------------------------------------------|
-  | ~overlap~          | ~float~ | ~(ao.num, ao.num)~ | $\langle p \vert q \rangle$                            |
+  | ~overlap~             | ~float~ | ~(ao.num, ao.num)~ | $\langle p \vert q \rangle$  (real part, general case)                            |
-  | ~kinetic~          | ~float~ | ~(ao.num, ao.num)~ | $\langle p \vert \hat{T}_e \vert q \rangle$            |
+  | ~kinetic~             | ~float~ | ~(ao.num, ao.num)~ | $\langle p \vert \hat{T}_e \vert q \rangle$  (real part, general case)            |
-  | ~potential_n_e~    | ~float~ | ~(ao.num, ao.num)~ | $\langle p \vert \hat{V}_{\text{ne}} \vert q \rangle$  |
+  | ~potential_n_e~       | ~float~ | ~(ao.num, ao.num)~ | $\langle p \vert \hat{V}_{\text{ne}} \vert q \rangle$  (real part, general case)  |
-  | ~ecp~              | ~float~ | ~(ao.num, ao.num)~ | $\langle p \vert \hat{V}_{\text{ecp}} \vert q \rangle$ |
+  | ~ecp~                 | ~float~ | ~(ao.num, ao.num)~ | $\langle p \vert \hat{V}_{\text{ecp}} \vert q \rangle$  (real part, general case) |
-  | ~core_hamiltonian~ | ~float~ | ~(ao.num, ao.num)~ | $\langle p \vert \hat{h} \vert q \rangle$              |
+  | ~core_hamiltonian~    | ~float~ | ~(ao.num, ao.num)~ | $\langle p \vert \hat{h} \vert q \rangle$  (real part, general case)              |
+  | ~overlap_im~          | ~float~ | ~(ao.num, ao.num)~ | $\langle p \vert q \rangle$ (imaginary part)  (imaginary part)                    |
+  | ~kinetic_im~          | ~float~ | ~(ao.num, ao.num)~ | $\langle p \vert \hat{T}_e \vert q \rangle$   (imaginary part)                    |
+  | ~potential_n_e_im~    | ~float~ | ~(ao.num, ao.num)~ | $\langle p \vert \hat{V}_{\text{ne}} \vert q \rangle$  (imaginary part)           |
+  | ~ecp_im~              | ~float~ | ~(ao.num, ao.num)~ | $\langle p \vert \hat{V}_{\text{ECP}} \vert q \rangle$  (imaginary part)          |
+  | ~core_hamiltonian_im~ | ~float~ | ~(ao.num, ao.num)~ | $\langle p \vert \hat{h} \vert q \rangle$ (imaginary part)                        |
 
    #+CALL: json(data=ao_1e_int, title="ao_1e_int")
 
@@ -506,11 +525,16 @@ prim_factor =
    :results:
    #+begin_src python :tangle trex.json
        "ao_1e_int": {
-                    "overlap" : [ "float", [ "ao.num", "ao.num" ] ]
+                       "overlap" : [ "float", [ "ao.num", "ao.num" ] ]
-         ,          "kinetic" : [ "float", [ "ao.num", "ao.num" ] ]
+         ,             "kinetic" : [ "float", [ "ao.num", "ao.num" ] ]
-         ,    "potential_n_e" : [ "float", [ "ao.num", "ao.num" ] ]
+         ,       "potential_n_e" : [ "float", [ "ao.num", "ao.num" ] ]
-         ,              "ecp" : [ "float", [ "ao.num", "ao.num" ] ]
+         ,                 "ecp" : [ "float", [ "ao.num", "ao.num" ] ]
-         , "core_hamiltonian" : [ "float", [ "ao.num", "ao.num" ] ]
+         ,    "core_hamiltonian" : [ "float", [ "ao.num", "ao.num" ] ]
+         ,          "overlap_im" : [ "float", [ "ao.num", "ao.num" ] ]
+         ,          "kinetic_im" : [ "float", [ "ao.num", "ao.num" ] ]
+         ,    "potential_n_e_im" : [ "float", [ "ao.num", "ao.num" ] ]
+         ,              "ecp_im" : [ "float", [ "ao.num", "ao.num" ] ]
+         , "core_hamiltonian_im" : [ "float", [ "ao.num", "ao.num" ] ]
        } ,
    #+end_src
    :end:
@@ -556,30 +580,36 @@ prim_factor =
 * Molecular orbitals (mo group)
 
   #+NAME: mo
-  | Variable      | Type    | Dimensions         | Description                                                              |
+  | Variable         | Type    | Dimensions         | Description                                                              |
-  |---------------+---------+--------------------+--------------------------------------------------------------------------|
+  |------------------+---------+--------------------+--------------------------------------------------------------------------|
-  | ~type~        | ~str~   |                    | Free text to identify the set of MOs (HF, Natural, Local, CASSCF, /etc/) |
+  | ~type~           | ~str~   |                    | Free text to identify the set of MOs (HF, Natural, Local, CASSCF, /etc/) |
-  | ~num~         | ~dim~   |                    | Number of MOs                                                            |
+  | ~num~            | ~dim~   |                    | Number of MOs                                                            |
-  | ~coefficient~ | ~float~ | ~(ao.num, mo.num)~ | MO coefficients                                                          |
+  | ~coefficient~    | ~float~ | ~(ao.num, mo.num)~ | MO coefficients (real part, general case)                                |
-  | ~class~       | ~str~   | ~(mo.num)~         | Choose among: Core, Inactive, Active, Virtual, Deleted                   |
+  | ~coefficient_im~ | ~float~ | ~(ao.num, mo.num)~ | MO coefficients (imaginary part, for periodic calculations)              |
-  | ~symmetry~    | ~str~   | ~(mo.num)~         | Symmetry in the point group                                              |
+  | ~class~          | ~str~   | ~(mo.num)~         | Choose among: Core, Inactive, Active, Virtual, Deleted                   |
-  | ~occupation~  | ~float~ | ~(mo.num)~         | Occupation number                                                        |
+  | ~symmetry~       | ~str~   | ~(mo.num)~         | Symmetry in the point group                                              |
+  | ~occupation~     | ~float~ | ~(mo.num)~         | Occupation number                                                        |
+  | ~energy~         | ~float~ | ~(mo.num)~         | For canonical MOs, corresponding eigenvalue                              |
+  | ~spin~           | ~int~   | ~(mo.num)~         | For UHF wave functions, 0 is $\alpha$ and 1 is $\beta$                   |
 
   #+CALL: json(data=mo, title="mo")
 
   #+RESULTS:
-  :RESULTS:
+  :results:
   #+begin_src python :tangle trex.json
       "mo": {
-		 "type" : [ "str"  , []                     ]
+                    "type" : [ "str"  , []                     ]
-	,         "num" : [ "dim"  , []                     ]
+        ,            "num" : [ "dim"  , []                     ]
-	, "coefficient" : [ "float", [ "mo.num", "ao.num" ] ]
+        ,    "coefficient" : [ "float", [ "mo.num", "ao.num" ] ]
-	,       "class" : [ "str"  , [ "mo.num" ]           ]
+        , "coefficient_im" : [ "float", [ "mo.num", "ao.num" ] ]
-	,    "symmetry" : [ "str"  , [ "mo.num" ]           ]
+        ,          "class" : [ "str"  , [ "mo.num" ]           ]
-	,  "occupation" : [ "float", [ "mo.num" ]           ]
+        ,       "symmetry" : [ "str"  , [ "mo.num" ]           ]
+        ,     "occupation" : [ "float", [ "mo.num" ]           ]
+        ,         "energy" : [ "float", [ "mo.num" ]           ]
+        ,           "spin" : [ "int"  , [ "mo.num" ]           ]
       } ,
   #+end_src
-  :END:
+  :end:
 
 ** One-electron integrals (~mo_1e_int~ group)
 
@@ -588,13 +618,18 @@ prim_factor =
    the basis of molecular orbitals.
 
    #+NAME: mo_1e_int
-  | Variable           | Type    | Dimensions         | Description                                            |
+  | Variable              | Type    | Dimensions         | Description                                                                       |
-  |--------------------+---------+--------------------+--------------------------------------------------------|
+  |-----------------------+---------+--------------------+-----------------------------------------------------------------------------------|
-  | ~overlap~          | ~float~ | ~(mo.num, mo.num)~ | $\langle i \vert j \rangle$                            |
+  | ~overlap~             | ~float~ | ~(mo.num, mo.num)~ | $\langle i \vert j \rangle$  (real part, general case)                            |
-  | ~kinetic~          | ~float~ | ~(mo.num, mo.num)~ | $\langle i \vert \hat{T}_e \vert j \rangle$            |
+  | ~kinetic~             | ~float~ | ~(mo.num, mo.num)~ | $\langle i \vert \hat{T}_e \vert j \rangle$ (real part, general case)             |
-  | ~potential_n_e~    | ~float~ | ~(mo.num, mo.num)~ | $\langle i \vert \hat{V}_{\text{ne}} \vert j \rangle$  |
+  | ~potential_n_e~       | ~float~ | ~(mo.num, mo.num)~ | $\langle i \vert \hat{V}_{\text{ne}} \vert j \rangle$  (real part, general case)  |
-  | ~ecp~              | ~float~ | ~(mo.num, mo.num)~ | $\langle i \vert \hat{V}_{\text{ECP}} \vert j \rangle$ |
+  | ~ecp~                 | ~float~ | ~(mo.num, mo.num)~ | $\langle i \vert \hat{V}_{\text{ECP}} \vert j \rangle$  (real part, general case) |
-  | ~core_hamiltonian~ | ~float~ | ~(mo.num, mo.num)~ | $\langle i \vert \hat{h} \vert j \rangle$              |
+  | ~core_hamiltonian~    | ~float~ | ~(mo.num, mo.num)~ | $\langle i \vert \hat{h} \vert j \rangle$  (real part, general case)              |
+  | ~overlap_im~          | ~float~ | ~(mo.num, mo.num)~ | $\langle i \vert j \rangle$ (imaginary part)  (imaginary part)                    |
+  | ~kinetic_im~          | ~float~ | ~(mo.num, mo.num)~ | $\langle i \vert \hat{T}_e \vert j \rangle$   (imaginary part)                    |
+  | ~potential_n_e_im~    | ~float~ | ~(mo.num, mo.num)~ | $\langle i \vert \hat{V}_{\text{ne}} \vert j \rangle$  (imaginary part)           |
+  | ~ecp_im~              | ~float~ | ~(mo.num, mo.num)~ | $\langle i \vert \hat{V}_{\text{ECP}} \vert j \rangle$  (imaginary part)          |
+  | ~core_hamiltonian_im~ | ~float~ | ~(mo.num, mo.num)~ | $\langle i \vert \hat{h} \vert j \rangle$ (imaginary part)                        |
 
    #+CALL: json(data=mo_1e_int, title="mo_1e_int")
 
@@ -602,26 +637,41 @@ prim_factor =
    :results:
    #+begin_src python :tangle trex.json
        "mo_1e_int": {
-                    "overlap" : [ "float", [ "mo.num", "mo.num" ] ]
+                       "overlap" : [ "float", [ "mo.num", "mo.num" ] ]
-         ,          "kinetic" : [ "float", [ "mo.num", "mo.num" ] ]
+         ,             "kinetic" : [ "float", [ "mo.num", "mo.num" ] ]
-         ,    "potential_n_e" : [ "float", [ "mo.num", "mo.num" ] ]
+         ,       "potential_n_e" : [ "float", [ "mo.num", "mo.num" ] ]
-         ,              "ecp" : [ "float", [ "mo.num", "mo.num" ] ]
+         ,                 "ecp" : [ "float", [ "mo.num", "mo.num" ] ]
-         , "core_hamiltonian" : [ "float", [ "mo.num", "mo.num" ] ]
+         ,    "core_hamiltonian" : [ "float", [ "mo.num", "mo.num" ] ]
+         ,          "overlap_im" : [ "float", [ "mo.num", "mo.num" ] ]
+         ,          "kinetic_im" : [ "float", [ "mo.num", "mo.num" ] ]
+         ,    "potential_n_e_im" : [ "float", [ "mo.num", "mo.num" ] ]
+         ,              "ecp_im" : [ "float", [ "mo.num", "mo.num" ] ]
+         , "core_hamiltonian_im" : [ "float", [ "mo.num", "mo.num" ] ]
        } ,
    #+end_src
    :end:
 
 ** Two-electron integrals (~mo_2e_int~ group)
 
-   The operators as the same as those defined in the
+   The operators are the same as those defined in the
    [[#ao_two_e][AO two-electron integrals section]]. Here, the integrals are given in
    the basis of molecular orbitals.
 
+   The Cholesky decomposition of the integrals can also be stored:
+
+   \[
+   \A_{ijkl} = \sum_{\alpha} G_{il\alpha} G_{jl\alpha}
+   \]
+
    #+NAME: mo_2e_int
-  | Variable | Type           | Dimensions                         | Description                             |
+  | Variable              | Type           | Dimensions                                        | Description                                   |
-  |----------+----------------+------------------------------------+-----------------------------------------|
+  |-----------------------+----------------+---------------------------------------------------+-----------------------------------------------|
-  | ~eri~    | ~float sparse~ | ~(mo.num, mo.num, mo.num, mo.num)~ | Electron repulsion integrals            |
+  | ~eri~                 | ~float sparse~ | ~(mo.num, mo.num, mo.num, mo.num)~                | Electron repulsion integrals                  |
-  | ~eri_lr~ | ~float sparse~ | ~(mo.num, mo.num, mo.num, mo.num)~ | Long-range Electron repulsion integrals |
+  | ~eri_lr~              | ~float sparse~ | ~(mo.num, mo.num, mo.num, mo.num)~                | Long-range Electron repulsion integrals       |
+  | ~eri_cholesky_num~    | ~dim~          |                                                   | Number of Cholesky vectors for ERI            |
+  | ~eri_cholesky~        | ~float sparse~ | ~(mo.num, mo.num, mo_2e_int.eri_cholesky_num)~    | Cholesky decomposition of the ERI             |
+  | ~eri_lr_cholesky_num~ | ~dim~          |                                                   | Number of Cholesky vectors for long range ERI |
+  | ~eri_lr_cholesky~     | ~float sparse~ | ~(mo.num, mo.num, mo_2e_int.eri_lr_cholesky_num)~ | Cholesky decomposition of the long range ERI  |
 
    #+CALL: json(data=mo_2e_int, title="mo_2e_int")
 
@@ -629,19 +679,141 @@ prim_factor =
    :results:
    #+begin_src python :tangle trex.json
        "mo_2e_int": {
-              "eri" : [ "float sparse", [ "mo.num", "mo.num", "mo.num", "mo.num" ] ]
+                           "eri" : [ "float sparse", [ "mo.num", "mo.num", "mo.num", "mo.num" ]              ]
-         , "eri_lr" : [ "float sparse", [ "mo.num", "mo.num", "mo.num", "mo.num" ] ]
+         ,              "eri_lr" : [ "float sparse", [ "mo.num", "mo.num", "mo.num", "mo.num" ]              ]
+         ,    "eri_cholesky_num" : [ "dim"         , []                                                      ]
+         ,        "eri_cholesky" : [ "float sparse", [ "mo_2e_int.eri_cholesky_num", "mo.num", "mo.num" ]    ]
+         , "eri_lr_cholesky_num" : [ "dim"         , []                                                      ]
+         ,     "eri_lr_cholesky" : [ "float sparse", [ "mo_2e_int.eri_lr_cholesky_num", "mo.num", "mo.num" ] ]
        } ,
    #+end_src
    :end:
 
-* TODO Slater determinants
+* Slater determinants (determinant group)
+
+  The configuration interaction (CI) wave function $\Psi$
+  can be expanded in the basis of Slater determinants $D_I$ as follows
+
+  \[
+  \Psi = \sum_I C_I D_I
+  \]
+
+  For relatively small expansions, a given determinant can be represented as a list of occupied orbitals.
+  However, this becomes unfeasible for larger expansions and requires more advanced data structures.
+  The bit field representation is used here, namely a given determinant is represented as $N_{\text{int}}$
+  64-bit integers where j-th bit is set to 1 if there is an electron in the j-th orbital and 0 otherwise.
+  This gives access to larger determinant expansions by optimising the storage of the determinant lists
+  in the memory.
+
+  \[
+  D_I = \alpha_1 \alpha_2 \ldots \alpha_{n_\uparrow} \beta_1 \beta_2 \ldots \beta_{n_\downarrow}
+  \]
+
+  where $\alpha$ and $\beta$ denote \uparrow-spin and \downarrow-spin electrons, respectively,
+  $n_\uparrow$ and $n_\downarrow$ correspond to ~electron.up_num~ and ~electron.dn_num~, respectively.
+
+  Note: the ~special~ attribute is present in the types, meaning that the source node is not
+  produced by the code generator.
+
+  An illustration on how to read determinants is presented in the [[./examples.html][examples]].
+
+  #+NAME: determinant
+  | Variable      | Type             | Dimensions          | Description                                            |
+  |---------------+------------------+---------------------+--------------------------------------------------------|
+  | ~num~         | ~dim readonly~   |                     | Number of determinants                                 |
+  | ~list~        | ~int special~    | ~(determinant.num)~ | List of determinants as integer bit fields             |
+  | ~coefficient~ | ~float buffered~ | ~(determinant.num)~ | Coefficients of the determinants from the CI expansion |
+
+  #+CALL: json(data=determinant, title="determinant")
+
+  #+RESULTS:
+  :results:
+  #+begin_src python :tangle trex.json
+      "determinant": {
+		  "num" : [ "dim readonly"  , []                    ]
+	,        "list" : [ "int special"   , [ "determinant.num" ] ]
+	, "coefficient" : [ "float buffered", [ "determinant.num" ] ]
+      } ,
+  #+end_src
+  :end:
+
+* Configuration state functions (csf group)
+
+  The configuration interaction (CI) wave function $\Psi$ can be
+  expanded in the basis of [[https://en.wikipedia.org/wiki/Configuration_state_function][configuration state functions]] (CSFs)
+  $\Psi_I$ as follows
+
+  \[
+  \Psi = \sum_I C_I \psi_I.
+  \]
+
+  Each CSF is a linear combination of Slater determinants. Slater
+  determinants are stored in the =determinant= section. In this group
+  we store the CI coefficients in the basis of CSFs, and the
+  matrix $\langle D_I | \psi_J \rangle$ needed to project the CSFs in
+  the basis of Slater determinants.
+
+  #+NAME: csf
+  | Variable          | Type             | Dimensions                  | Description                                    |
+  |-------------------+------------------+-----------------------------+------------------------------------------------|
+  | ~num~             | ~dim readonly~   |                             | Number of CSFs                                 |
+  | ~coefficient~     | ~float buffered~ | ~(csf.num)~                 | Coefficients of the CSFs from the CI expansion |
+  | ~det_coefficient~ | ~float sparse~   | ~(determinant.num,csf.num)~ | Projection on the determinant basis            |
+
+  #+CALL: json(data=csf, title="csf")
+
+  #+RESULTS:
+  :results:
+  #+begin_src python :tangle trex.json
+      "csf": {
+		      "num" : [ "dim readonly"  , []                               ]
+	,     "coefficient" : [ "float buffered", [ "csf.num" ]                    ]
+	, "det_coefficient" : [ "float sparse"  , [ "csf.num", "determinant.num" ] ]
+      } ,
+  #+end_src
+  :end:
+
+* Excited states (state group)
+
+  This group contains information about excited state. Since TREXIO version 2.3.0
+  the state-specific data (e.g. CI/CSF coeffcients, RDMs) is written in a separate
+  file in order to avoid over-complicated internal logics and global state switches.
+
+  The ~file_name~ and ~label~ arrays have to be written only for the master file,
+  e.g. the one containing the ground state wave function.
+  The ~id~ and ~current_label~ attributes have to be specified for each file
+  (containing both ground and excited state data).
+
+  #+NAME: state
+  | Variable        | Type  | Dimensions    | Description                                                                                   |
+  |-----------------+-------+---------------+-----------------------------------------------------------------------------------------------|
+  | ~num~           | ~dim~ |               | Number of states (including the ground state)                                                 |
+  | ~id~            | ~int~ |               | Index of a current state (0 is ground state)                                                  |
+  | ~label~         | ~str~ | ~(state.num)~ | Labels of all states related to this file (e.g. 'S' for singlets)                             |
+  | ~current_label~ | ~str~ |               | Labels of the current state that is in a file                                                 |
+  | ~file_name~     | ~str~ | ~(state.num)~ | Names of the TREXIO files linked to the current one (i.e. containing data for excited states) |
+
+  #+CALL: json(data=state, title="state")
+
+  #+RESULTS:
+  :results:
+  #+begin_src python :tangle trex.json
+      "state": {
+		    "num" : [ "dim", []              ]
+	,            "id" : [ "int", []              ]
+	,         "label" : [ "str", [ "state.num" ] ]
+	, "current_label" : [ "str", []              ]
+	,     "file_name" : [ "str", [ "state.num" ] ]
+      } ,
+  #+end_src
+  :end:
+
 * Reduced density matrices (rdm group)
 
   The reduced density matrices are defined in the basis of molecular
   orbitals.
 
-  The $\uparrow$-spin and $\downarrow$-spin components of the one-body
+  The \uparrow-spin and \downarrow-spin components of the one-body
   density matrix are given by
   \begin{eqnarray*}
     \gamma_{ij}^{\uparrow}   &=& \langle \Psi | \hat{a}^{\dagger}_{j\alpha}\, \hat{a}_{i\alpha} | \Psi \rangle \\
@@ -677,17 +849,43 @@ prim_factor =
       \frac{1}{2} \sum_{ijlk} \Gamma_{ijkl} \langle k l | i j \rangle
   \]
 
+
+  To compress the storage, the Cholesky decomposition of the RDMs can
+  be stored:
+
+  \[
+    \Gamma_{ijkl} = \sum_{\alpha} G_{ij\alpha} G_{kl\alpha}
+  \]
+
+  Warning: as opposed to electron repulsion integrals, the
+  decomposition is made such that the Cholesky vectors are expanded
+  in a two-electron basis
+  $f_{ij}(\mathbf{r}_1,\mathbf{r}_2) = \phi_i(\mathbf{r}_1) \phi_j(\mathbf{r}_2)$,
+  whereas in electron repulsion integrals each Cholesky vector is
+  expressed in a basis of a one-electron function
+  $g_{ik}(\mathbf{r}_1) = \phi_i(\mathbf{r}_1) \phi_k(\mathbf{r}_1)$.
+  
   #+NAME: rdm
-  | Variable  | Type           | Dimensions                         | Description                                                           |
+  | Variable               | Type           | Dimensions                                   | Description                                                           |
-  |-----------+----------------+------------------------------------+-----------------------------------------------------------------------|
+  |------------------------+----------------+----------------------------------------------+-----------------------------------------------------------------------|
-  | ~1e~      | ~float~        | ~(mo.num, mo.num)~                 | One body density matrix                                               |
+  | ~1e~                   | ~float~        | ~(mo.num, mo.num)~                           | One body density matrix                                               |
-  | ~1e_up~   | ~float~        | ~(mo.num, mo.num)~                 | \uparrow-spin component of the one body density matrix                |
+  | ~1e_up~                | ~float~        | ~(mo.num, mo.num)~                           | \uparrow-spin component of the one body density matrix                |
-  | ~1e_dn~   | ~float~        | ~(mo.num, mo.num)~                 | \downarrow-spin component of the one body density matrix              |
+  | ~1e_dn~                | ~float~        | ~(mo.num, mo.num)~                           | \downarrow-spin component of the one body density matrix              |
-  | ~2e~      | ~float sparse~ | ~(mo.num, mo.num, mo.num, mo.num)~ | Two-body reduced density matrix (spin trace)                          |
+  | ~2e~                   | ~float sparse~ | ~(mo.num, mo.num, mo.num, mo.num)~           | Two-body reduced density matrix (spin trace)                          |
-  | ~2e_upup~ | ~float sparse~ | ~(mo.num, mo.num, mo.num, mo.num)~ | \uparrow\uparrow component of the two-body reduced density matrix     |
+  | ~2e_upup~              | ~float sparse~ | ~(mo.num, mo.num, mo.num, mo.num)~           | \uparrow\uparrow component of the two-body reduced density matrix     |
-  | ~2e_dndn~ | ~float sparse~ | ~(mo.num, mo.num, mo.num, mo.num)~ | \downarrow\downarrow component of the two-body reduced density matrix |
+  | ~2e_dndn~              | ~float sparse~ | ~(mo.num, mo.num, mo.num, mo.num)~           | \downarrow\downarrow component of the two-body reduced density matrix |
-  | ~2e_updn~ | ~float sparse~ | ~(mo.num, mo.num, mo.num, mo.num)~ | \uparrow\downarrow component of the two-body reduced density matrix   |
+  | ~2e_updn~              | ~float sparse~ | ~(mo.num, mo.num, mo.num, mo.num)~           | \uparrow\downarrow component of the two-body reduced density matrix   |
-  | ~2e_dnup~ | ~float sparse~ | ~(mo.num, mo.num, mo.num, mo.num)~ | \downarrow\uparrow component of the two-body reduced density matrix   |
+  | ~2e_dnup~              | ~float sparse~ | ~(mo.num, mo.num, mo.num, mo.num)~           | \downarrow\uparrow component of the two-body reduced density matrix   |
+  | ~2e_cholesky_num~      | ~dim~          |                                              | Number of Cholesky vectors                                            |
+  | ~2e_cholesky~          | ~float sparse~ | ~(mo.num, mo.num, rdm.2e_cholesky_num)~      | Cholesky decomposition of the Two-body RDM (spin trace)               |
+  | ~2e_upup_cholesky_num~ | ~dim~          |                                              | Number of Cholesky vectors                                            |
+  | ~2e_upup_cholesky~     | ~float sparse~ | ~(mo.num, mo.num, rdm.2e_upup_cholesky_num)~ | Cholesky decomposition of the Two-body RDM (\uparrow\uparrow)         |
+  | ~2e_dndn_cholesky_num~ | ~dim~          |                                              | Number of Cholesky vectors                                            |
+  | ~2e_dndn_cholesky~     | ~float sparse~ | ~(mo.num, mo.num, rdm.2e_dndn_cholesky_num)~ | Cholesky decomposition of the Two-body RDM (\downarrow\downarrow)     |
+  | ~2e_updn_cholesky_num~ | ~dim~          |                                              | Number of Cholesky vectors                                            |
+  | ~2e_updn_cholesky~     | ~float sparse~ | ~(mo.num, mo.num, rdm.2e_updn_cholesky_num)~ | Cholesky decomposition of the Two-body RDM (\uparrow\downarrow)       |
+  | ~2e_dnup_cholesky_num~ | ~dim~          |                                              | Number of Cholesky vectors                                            |
+  | ~2e_dnup_cholesky~     | ~float sparse~ | ~(mo.num, mo.num, rdm.2e_dnup_cholesky_num)~ | Cholesky decomposition of the Two-body RDM (\downarrow\uparrow)       |
 
   #+CALL: json(data=rdm, title="rdm")
 
@@ -695,14 +893,66 @@ prim_factor =
   :results:
   #+begin_src python :tangle trex.json
       "rdm": {
-               "1e" : [ "float"       , [ "mo.num", "mo.num" ]                     ]
+                            "1e" : [ "float"       , [ "mo.num", "mo.num" ]                             ]
-        ,   "1e_up" : [ "float"       , [ "mo.num", "mo.num" ]                     ]
+        ,                "1e_up" : [ "float"       , [ "mo.num", "mo.num" ]                             ]
-        ,   "1e_dn" : [ "float"       , [ "mo.num", "mo.num" ]                     ]
+        ,                "1e_dn" : [ "float"       , [ "mo.num", "mo.num" ]                             ]
-        ,      "2e" : [ "float sparse", [ "mo.num", "mo.num", "mo.num", "mo.num" ] ]
+        ,                   "2e" : [ "float sparse", [ "mo.num", "mo.num", "mo.num", "mo.num" ]         ]
-        , "2e_upup" : [ "float sparse", [ "mo.num", "mo.num", "mo.num", "mo.num" ] ]
+        ,              "2e_upup" : [ "float sparse", [ "mo.num", "mo.num", "mo.num", "mo.num" ]         ]
-        , "2e_dndn" : [ "float sparse", [ "mo.num", "mo.num", "mo.num", "mo.num" ] ]
+        ,              "2e_dndn" : [ "float sparse", [ "mo.num", "mo.num", "mo.num", "mo.num" ]         ]
-        , "2e_updn" : [ "float sparse", [ "mo.num", "mo.num", "mo.num", "mo.num" ] ]
+        ,              "2e_updn" : [ "float sparse", [ "mo.num", "mo.num", "mo.num", "mo.num" ]         ]
-        , "2e_dnup" : [ "float sparse", [ "mo.num", "mo.num", "mo.num", "mo.num" ] ]
+        ,              "2e_dnup" : [ "float sparse", [ "mo.num", "mo.num", "mo.num", "mo.num" ]         ]
+        ,      "2e_cholesky_num" : [ "dim"         , []                                                 ]
+        ,          "2e_cholesky" : [ "float sparse", [ "rdm.2e_cholesky_num", "mo.num", "mo.num" ]      ]
+        , "2e_upup_cholesky_num" : [ "dim"         , []                                                 ]
+        ,     "2e_upup_cholesky" : [ "float sparse", [ "rdm.2e_upup_cholesky_num", "mo.num", "mo.num" ] ]
+        , "2e_dndn_cholesky_num" : [ "dim"         , []                                                 ]
+        ,     "2e_dndn_cholesky" : [ "float sparse", [ "rdm.2e_dndn_cholesky_num", "mo.num", "mo.num" ] ]
+        , "2e_updn_cholesky_num" : [ "dim"         , []                                                 ]
+        ,     "2e_updn_cholesky" : [ "float sparse", [ "rdm.2e_updn_cholesky_num", "mo.num", "mo.num" ] ]
+        , "2e_dnup_cholesky_num" : [ "dim"         , []                                                 ]
+        ,     "2e_dnup_cholesky" : [ "float sparse", [ "rdm.2e_dnup_cholesky_num", "mo.num", "mo.num" ] ]
+      } ,
+  #+end_src
+  :end:
+
+* Cell (cell group)
+
+  #+NAME: cell
+  | Variable | Type    | Dimensions | Description             |
+  |----------+---------+------------+-------------------------|
+  | ~a~      | ~float~ | ~(3)~      | First unit cell vector  |
+  | ~b~      | ~float~ | ~(3)~      | Second unit cell vector |
+  | ~c~      | ~float~ | ~(3)~      | Third unit cell vector  |
+
+  #+CALL: json(data=cell, title="cell")
+
+  #+RESULTS:
+  :results:
+  #+begin_src python :tangle trex.json
+      "cell": {
+          "a" : [ "float", [ "3" ] ]
+        , "b" : [ "float", [ "3" ] ]
+        , "c" : [ "float", [ "3" ] ]
+      } ,
+  #+end_src
+  :end:
+
+* Periodic boundary calculations (pbc group)
+
+  #+NAME: pbc
+  | Variable   | Type    | Dimensions | Description             |
+  |------------+---------+------------+-------------------------|
+  | ~periodic~ | ~int~   |            | ~1~: true or ~0~: false |
+  | ~k_point~  | ~float~ | ~(3)~      | k-point sampling        |
+
+  #+CALL: json(data=pbc, title="pbc")
+
+  #+RESULTS:
+  :results:
+  #+begin_src python :tangle trex.json
+      "pbc": {
+          "periodic" : [ "int"  , []      ]
+        ,  "k_point" : [ "float", [ "3" ] ]
       } ,
   #+end_src
   :end:
@@ -724,9 +974,9 @@ prim_factor =
   | ~point~  | ~float~ | ~(3, electron.num, qmc.num)~ | 3N-dimensional points                 |
   | ~psi~    | ~float~ | ~(qmc.num)~                  | Wave function evaluated at the points |
   | ~e_loc~  | ~float~ | ~(qmc.num)~                  | Local energy evaluated at the points  |
-   
+
    #+CALL: json(data=qmc, title="qmc", last=1)
-   
+
    #+RESULTS:
    :results:
    #+begin_src python :tangle trex.json