This tool sets up an ORCA calculation using the q-vSZP basis set (submitted to The Journal of Chemical Physics). It is intended to work with ORCA version 5.0.4 and higher. The project depends on other subprojects, the most important being tblite (https://github.com/tblite/tblite) and stdlib (https://github.com/fortran-lang/stdlib).

The basis sets itself is located in q-vSZP_basis/. Besides the full q-vSZP basis set, also a version without polarization functions (basisq_wopol) is available.

The use of the statically-linked release binary [qvSZP] is recommended. The binary has to be added to a location belonging to your $PATH variable.

To build this project from the source code in this repository, you need to have one of the following two build systems:

• meson version 0.57.2 or newer, with a build-system backend, i.e. ninja version 1.10 or newer OR
• fpm version 0.9.0 or newer

Moreover, you need to have:

• a Fortran compiler supporting Fortran 2008
• a LAPACK / BLAS provider, like MKL or OpenBLAS
• for meson required, for fpm not required: Installed Fortran standard library (https://github.com/fortran-lang/stdlib):
  • git clone [email protected]:fortran-lang/stdlib.git and move into the new directory.
  • FC=ifort CC=icc CXX=icpc cmake -B build -DBUILD_SHARED_LIBS=on -DCMAKE_INSTALL_PREFIX=$HOME/.local (if you have problems, try to omit -DBUILD_SHARED_LIBS=on).
  • cmake --build build
  • cmake --install build

To build the project, you can use the Fortran Package Manager (https://github.com/fortran-lang/fpm) in version 0.9 or newer. To install the project in your preferred path, just use

fpm install -profile release -prefix [path]

More information about FPM can be found in the respective documentation.

You can use meson to build the project from source. Caution: For building with meson, the Fortran Standard Library (stdlib) has to be installed beforehand (see below). To install the qvSZP project in your preferred path (assuming the use of Intel compilers), set up a build in the (new) directory _build with:

FC=ifort CC=icc CXX=icpc meson setup _build --buildtype release --prefix=[path] -Dfortran_link_args=-qopenmp

You can compile (and install) the build with the following commands:

meson compile -C _build
meson install -C _build

If you want to set up a static compilation, replace the above meson setup with the following:

FC=ifort CC=icc CXX=icpc meson setup _build --buildtype release -Dfortran_link_args="-static -qopenmp -lifcoremt" --default-library=static --prefix=[path]

To set up an input file using the q-vSZP basis set for a given geometry, you have to execute qvSZP in a directory with a molecular structure file (can be either .xyz, coord, or other common formats (see mctc-lib (https://github.com/grimme-lab/mctc-lib) for possible formats).

You need the files:

• .basisq and .ecpq in a known location (default: $HOME/<file>. The individual location of the files can be provided with the sample input below (or press --help).

Example program command-line calls:

qvSZP --struc coord.benzene
qvSZP --struc ch3.xyz --bfile /home/$USER/basissets/basisq --efile /home/$USER/basissets/ecpq --chrg -1

If no --struc file is explicitly given, qvSZP assumes a coord file.

See the -help flag for further input possibilities. If you should observe instabilities with the PModel guess in ORCA, try to use qvSZP together with the --suggestedguess flag or provide an individual guess option with --guess.