QMC=Chem : Quantum Monte Carlo for Chemistry ============================================ **This repository is under migration to GitHub. Please be patient...** QMC=Chem is the quantum Monte Carlo program of the [Toulouse (France) group](http://qmcchem.ups-tlse.fr). It is meant to be used in the *post-Full-CI* context : a quasi-Full-CI calculation is done with the [quantum package](https://github.com/LCPQ/quantum_package), and this wave function is used as a trial wave function for the fixed-node diffusion Monte Carlo algorithm. * Parallel efficiency of 98.3% on 16_000 cores * The load balancing is optimal: the workers always work 100% of the time, independently of their respective CPU speeds * Efficient: 0.96 Pflops/s on 76_800 cores of Curie in 2011 * All network communications are non-blocking, with the [ZeroMQ](http://zeromq.org) library * All the implemented algorithms are CPU-bound : the only limit is the available CPU time * The number of simultaneous worker nodes can be variable during a calculation * Fully fault-tolerant (crashing nodes don't stop the running calculation) * QMC=Chem has been used in grid environments (EGI european grid) and in Cloud environments (rance Grilles) coupled to supercomputers Warnings: * QMC=Chem is under the GPLv2 license. Any modifications to or software including (via compiler) GPL-licensed code must also be made available under the GPL along with build & install instructions. * Pseudopotentials are about to change in EZFIO database. Current calculations will not be compatible with future versions Requirements ------------ * [Ninja build tool](http://github.com/martine/ninja) * [Ocaml compiler with Opam and Core library](http://github.com/ocaml) * [ZeroMQ high performance communication library](http://www.zeromq.org) * [F77_ZMQ ZeroMQ Fortran interface](http://github.com/scemama/f77_zmq/) * [IRPF90 Fortran code generator](http://irpf90.ups-tlse.fr) * [EZFIO Easy Fortran I/O library generator](http://github.com/scemama/EZFIO) * GNU C++ Compiler (g++) for ZeroMQ * Python >= 2.6 for install scripts * Bash * Fortran compiler, Intel Fortran recommended * Lapack library, Intel MKL recommended Most of the dependencies are open-source will be downloaded automatically. The Fortran and C++ compilers, Python and Bash interpreters and the Lapack library need to be installed manually by the user. Installation ------------ The ``make.config`` file contains compiler specific parameters. The ``configure.sh`` script will first download the [Ninja](http://github.com/martine/ninja) build tool, and will then run Ninja using the ``install/build.ninja`` file. The configuration script will work in the ``install`` directory. It will first download into the ``install/Downloads`` directory everything that needs to be installed. The building of the dependencies takes place in the ``install/_build`` directory, and the packages that are being installed can be followed by looking at the log files in this directory. When a package was successfully installed, a ``*.ok`` file is created and the log file is deleted. Before using or compiling QMC=Chem, environment variables need to be loaded. The environment variables are located in the ``qmcchemrc`` file: ```bash $ source qmcchemrc ``` To compile the program, run ```bash $ ninja ``` Example of a QMC=Chem calculation --------------------------------- Calculation with the quantum package ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1) Create the ``xyz`` file containing the nuclear coordinates of the system ```bash $ cat > h2o.xyz << EOF 3 Water molecule O 0. 0. 0. H 0.9572 0. 0. H -0.239987 0.926627 0. EOF ``` 2) Choose a suitable basis set and create the [EZFIO database](https://github.com/LCPQ/ezfio) ```bash $ qp_create_ezfio_from_xyz -b cc-pvdz h2o.xyz -o h2o ``` 3) Run the SCF calculation ```bash $ qp_run SCF h2o ``` 4) Run the CIPSI calculation ```bash $ qp_run full_ci h2o ``` 5) Transform the input for use in QMC=Chem ```bash $ qp_run save_for_qmcchem h2o ``` FN-DMC calculation with QMC=Chem ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Before using QMC=Chem, you need to load the environment variables: ```bash $ source qmcchem.rc ``` In QMC=Chem, everything goes through the use of the ``qmcchem`` command. When a command is run with no arguments, it prints a help message. This is mainly the manual of QMC=Chem. For example: ```bash $ qmcchem QMC=Chem command qmcchem SUBCOMMAND === subcommands === debug Debug ZeroMQ communications edit Edit input data md5 Manipulate input MD5 keys result Displays the results computed in an EZFIO directory. run Run a calculation stop Stop a running calculation version print version information help explain a given subcommand (perhaps recursively) missing subcommand for command qmcchem $ qmcchem edit Run a calculation qmcchem run EZFIO_FILE Run QMC=Chem === flags === [-a] Add more resources to a running calculation. [-d] Start a dataserver process on the local host. [-q ] Start a qmc process on the local host. [-s ] Start a qmc process on . [-help] print this help text and exit (alias: -?) missing anonymous argument: EZFIO_FILE ``` 1) Set the parameters for a VMC calculation to create initial walker positions ```bash $ qmcchem edit -h Edit input data qmcchem edit EZFIO_FILE [INPUT] Edit input data === flags === [-c] Clear blocks [-e energy] Fixed reference energy to normalize DMC weights [-f 0|1] Correct wave function to verify electron-nucleus cusp condition [-j jastrow_type] Type of Jastrow factor [ None | Core | Simple ] [-l seconds] Length (seconds) of a block [-m method] QMC Method : [ VMC | DMC ] [-n norm] Truncation t of the wave function : Remove determinants with a contribution to the norm less than t [-s sampling] Sampling algorithm : [ Langevin | Brownian ] [-t seconds] Requested simulation time (seconds) [-ts time_step] Simulation time step [-w walk_num] Number of walkers per CPU core [-wt walk_num_tot] Total number of stored walkers for restart [-help] print this help text and exit (alias: -?) $ qmcchem edit h2o -f 1 -m VMC -n 1.e-5 -s Langevin -t 300 -l 10 ``` 3) Get info on the wave function ```bash $ qmcchem info h2o ``` 4) Run the VMC calculation ```bash $ qmcchem run h2o ``` 5) Set the correct parameters for FN-DMC ```bash $ qmcchem edit h2o -e -76.438 -m DMC -s Brownian -ts 3.e-4 -t 3600 -l 30 ``` 6) Run the FN-DMC calculation ```bash $ qmcchem run h2o ``` 7) Print the result ```bash $ qmcchem result h2o ``` References ---------- [Quantum Monte Carlo for large chemical systems: Implementing efficient strategies for petascale platforms and beyond](http://dx.doi.org/10.1002/jcc.23216) > Anthony Scemama , Michel Caffarel , Emmanuel Oseret and William Jalby (2013), in: Journal of Computational Chemistry, 34:11(938--951) [Quantum Monte Carlo with very large multideterminant wavefunctions](http://arxiv.org/abs/1509.03114) > Anthony Scemama , Thomas Applencourt , Emmanuel Giner and Michel Caffarel (2015), in: ArXiv ePrints:arXiv:1510.00730 [physics.chem-ph]