Installation and Configuration

This section provides detailed instructions for installing and configuring QMC=Chem, including prerequisites, supported platforms, and initial setup steps.

Requirements

Before installing QMC=Chem, ensure that the following prerequisites are met:

  • Bash: A Unix shell and command language.

  • Python3: Required for various scripting and automation tasks.

  • Fortran Compiler: Intel Fortran is recommended for optimal performance.

  • Lapack Library: Intel MKL is recommended for efficient numerical computations.

  • ZeroMQ: A high-performance communication library, essential for network communications. ZeroMQ Library

  • F77_ZMQ: A ZeroMQ Fortran interface. Download F77_ZMQ

  • QMCkl Library: A library for quantum Monte Carlo kernels. Download QMCkl

  • TREXIO Library: A library for managing quantum chemistry data. Download TREXIO

  • OCaml Compiler with Opam: Required for certain computational tasks. OCaml Compiler

To install the necessary OCaml packages, execute the following command:

opam install ocamlbuild cryptokit zmq sexplib ppx_sexp_conv ppx_deriving getopt trexio

For OCaml installation issues on x86 systems, consider downloading this archive and follow these steps:

tar --gunzip --extract --file opampack.tar.gz
cd opampack
./install.sh
export OPAMROOT="${PWD}"/opamroot
eval ("${OPAMROOT}"/opam env)

Installation Process

To compile QMC=Chem, execute the following commands:

./autogen.sh
./configure && make

After compilation, it’s necessary to set up the environment for QMC=Chem. The environment variables are specified in the qmcchemrc file:

source qmcchemrc

Set the QMCCHEM_NIC environment variable to the appropriate network interface, typically ib0 on HPC systems. If needed, set QMCCHEM_IO=b to store the results in binary format to accelerate post-processing.

Tuning for HPC Systems

For optimal performance, the Intel compiler is recommended. If using gfortran version 12 or higher, add the -fallow-argument-mismatch option.

Example configurations:

  • For Intel Fortran Compiler:

    ./configure FC=ifort FCFLAGS="-O2 -g -ip -ftz -finline -xCORE-AVX2 -mkl=sequential"

  • For GCC version 12 or higher:

    ./configure FCFLAGS="-fallow-argument-mismatch -g -O2 -ffast-math -march=native -fno-trapping-math -fno-math-errno -ftree-vectorize -fno-stack-protector -fopenmp"

File Preparation

To prepare files for QMC=Chem, the save_for_qmcchem plugin must be installed in Quantum Package:

qp plugins download https://gitlab.com/scemama/qp_plugins_scemama
qp plugins install qmcchem
cd $QP_ROOT/src/qmcchem
ninja

After completing a Quantum Package calculation, execute the following command to prepare the directory for QMC=Chem:

qp run save_for_qmcchem