diff --git a/.gitignore b/.gitignore
index ef95009..deb19d0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,7 +1,8 @@
 *.o
 *.mod
+*.dbg
 .vscode
 Slater*
 Updates*
-datasets/datasets.*
+datasets/dataset.*
 bin/
diff --git a/Makefile b/Makefile
index b47b608..ebfefa2 100644
--- a/Makefile
+++ b/Makefile
@@ -1,19 +1,37 @@
-## Compilers
-ARCH =
-CXX = clang++-7
-FC = flang-7
-H5CXX = h5c++
-
-## Compiler flags
-CXXFLAGS = -O0 
+## Compilers, compiler flags & external libs
+ifeq ($(ENV),INTEL)
+	CXX = icpc
+	FC = ifort
+	ARCH = -xCORE-AVX2
+	OPT = -O0
+	DEBUG = -debug full
+else ifeq ($(ENV),LLVM)
+	CXX = clang++
+	FC = flang
+	ARCH =
+	OPT = -O0
+	DEBUG = -g
+else ifeq ($(ENV),GNU)
+	CXX = g++
+	FC = gfortran
+	ARCH = -mavx
+	OPT = -O0
+	DEBUG = -g
+else
+    $(error No valid compiler environment set in $$ENV. First run: $$ source smvars.sh {intel | llvm | gnu})
+endif
+CXXFLAGS = $(OPT) $(ARCH) $(DEBUG)
 FFLAGS = $(CXXFLAGS)
+H5CXX = h5c++
 H5CXXFLAGS = $(CXXFLAGS) -fPIC
 FLIBS = -lstdc++
 
+## Includes and dependencies
 INCLUDE = -I $(INC_DIR)/
 DEPS_CXX = $(OBJ_DIR)/SM_MaponiA3.o $(OBJ_DIR)/SM_Standard.o
 DEPS_F = $(DEPS_CXX) $(OBJ_DIR)/SM_MaponiA3_mod.o $(OBJ_DIR)/Helpers_mod.o
 
+## Directory structure
 SRC_DIR := src
 TST_DIR := tests
 INC_DIR := include
@@ -32,7 +50,7 @@ EXEC := $(BIN_DIR)/cMaponiA3_test_3x3_3 \
 all: $(EXEC)
 
 clean:
-	@rm -vrf $(OBJ_DIR)
+	@rm -vrf $(OBJ_DIR) *.dbg
 
 distclean: clean
 	@rm -vrf $(BIN_DIR) \
@@ -46,7 +64,7 @@ $(BIN_DIR) $(OBJ_DIR):
 ### IMPLICIT BUILD RULES
 ## C++ objects
 $(OBJ_DIR)/%.o: $(TST_DIR)/%.cpp $(INC_DIR)/* | $(OBJ_DIR)
-	$(CXX) $(CXXFLAGS) $(ARCH) $(INCLUDE) -c -o $@ $<
+	$(CXX) $(CXXFLAGS) $(INCLUDE) -c -o $@ $<
 
 ## HDF5/C++ objects
 $(OBJ_DIR)/%_h5.o: $(TST_DIR)/%_h5.cpp $(INC_DIR)/* | $(OBJ_DIR)
@@ -54,19 +72,23 @@ $(OBJ_DIR)/%_h5.o: $(TST_DIR)/%_h5.cpp $(INC_DIR)/* | $(OBJ_DIR)
 
 ## Fortran modules
 $(OBJ_DIR)/%_mod.o: $(SRC_DIR)/%_mod.f90 | $(OBJ_DIR)
-	$(FC) $(FFLAGS) $(ARCH) -J$(OBJ_DIR)/ -c -o $@ $<
+ifeq ($(ENV),$(filter $(ENV),LLVM GNU))
+	$(FC) $(FFLAGS) -J $(OBJ_DIR)/ -c -o $@ $<
+else
+	$(FC) $(FFLAGS) -module $(OBJ_DIR)/ -c -o $@ $<
+endif
 
 ## Fortran objects
 $(OBJ_DIR)/%.o: $(TST_DIR)/%.f90 | $(OBJ_DIR)
-	$(FC) $(FFLAGS) $(ARCH) -I $(OBJ_DIR)/ -c -o $@ $<
+	$(FC) $(FFLAGS) -I $(OBJ_DIR)/ -c -o $@ $<
 
 ### EXPLICIT BUILD RULES
 ## special compiler flag -fPIC otherwise h5c++ builds fail
 $(OBJ_DIR)/SM_MaponiA3.o: $(SRC_DIR)/SM_MaponiA3.cpp $(INC_DIR)/* | $(OBJ_DIR)
-	$(CXX) $(CXXFLAGS) -fPIC $(ARCH) $(INCLUDE) -c -o $@ $<
+	$(CXX) $(CXXFLAGS) -fPIC $(INCLUDE) -c -o $@ $<
 
 $(OBJ_DIR)/SM_Standard.o: $(SRC_DIR)/SM_Standard.cpp $(INC_DIR)/* | $(OBJ_DIR)
-	$(CXX) $(CXXFLAGS) -fPIC $(ARCH) $(INCLUDE) -c -o $@ $<
+	$(CXX) $(CXXFLAGS) -fPIC $(INCLUDE) -c -o $@ $<
 
 
 #### LINKING
diff --git a/runtests.sh b/runtests.sh
deleted file mode 100755
index 11b3704..0000000
--- a/runtests.sh
+++ /dev/null
@@ -1,22 +0,0 @@
-#!/usr/bin/env bash
-
-start_cycle=$1
-stop_cycle=$2
-
-if [ "$#" -ne 2 ]
-then
-    echo "usage: ./run-tests.sh <start cycle> <stop cycle>"
-    exit 1
-fi
-
-if [ ! -f "bin/test_external_h5" ]
-then
-    make bin/test_external_h5
-fi
-
-cd datasets/
-
-for ((cycle = start_cycle; cycle < stop_cycle+1; cycle++))
-do
-    ../bin/test_external_h5 $cycle
-done
\ No newline at end of file
diff --git a/smvars.sh b/smvars.sh
new file mode 100644
index 0000000..88cc645
--- /dev/null
+++ b/smvars.sh
@@ -0,0 +1,40 @@
+#!/usr/bin/env bash
+
+ENV=$1
+
+PWD=$(pwd)
+SRCDIR=$(dirname $BASH_SOURCE)
+case $SRCDIR in
+	/*) SMROOT=$SRCDIR ;; ## sourced from absolute path
+	*) SMROOT=$PWD/$SRCDIR ;; ## sourced from relative path
+esac
+export SMROOT
+
+case $ENV in
+  intel)
+	export HDF5_CXX=icpc
+	export HDF5_CXXLINKER=icpc
+	export ENV=INTEL
+    ;;
+  llvm)
+	export HDF5_CXX=clang++
+	export HDF5_CXXLINKER=clang++
+	export ENV=LLVM
+    ;;
+  gnu)
+	export HDF5_CXX=g++
+	export HDF5_CXXLINKER=g++
+	export ENV=GNU
+	;;
+  *)
+    echo "Unknown environment descriptor given."
+	echo "Usage: source smvars.sh {intel | llvm | gnu}"
+	return 1
+	;;
+esac
+
+if [ -z "$SMVARS" ]
+then
+	export PATH=$SMROOT/bin:$PATH
+	export SMVARS=true
+fi
diff --git a/smvarsrc b/smvarsrc
deleted file mode 100644
index a4434e3..0000000
--- a/smvarsrc
+++ /dev/null
@@ -1,6 +0,0 @@
-#!/usr/bin/env bash
-
-export HDF5_CXX=icpc
-export HDF5_CXXLINKER=icpc
-
-export PATH=$PWD/bin:$PATH