qvSZP

This tool sets up an ORCA calculation using the q-vSZP basis set (J. Chem. Phys. 159, 164108 (2023)). 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 versions without polarization functions and without core electrons for f elements are available.

Installation

Building with Fortran package Manager

To build the project, you can use the Fortran Package Manager (https://github.com/fortran-lang/fpm) in version 0.9.0 or newer. To install the project in your preferred path, just use

fpm install -profile release -prefix [path]

Depending on your system, you might need to adapt the BLAS/LAPACK library in the fpm.toml file:

link=["lapack"] # or "openblas"

On macOS-arm64, the respective library is openblas. The build command is then:

fpm build --profile release --compiler gfortran-14 --c-compiler gcc-14 --link-flag "-L/opt/homebrew/opt/openblas/lib" --c-flag "-I/opt/homebrew/opt/openblas/include"

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

Usage

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.