Molden to Abins format converter

This script is intended to facilitate simulation of inelastic neutron scattering spectra from a file in Molden format.

Usage

By default, the script prints to standard output. From a unix-like environment this can be redirected to make a new .json file

molden_to_abins.py my_input.mol > my_output.json

or alternatively the --output parameter can be used.

molden_to_abins.py my_input.mol --output my_output.json

The resulting JSON file can be used with Mantid by selecting "JSON" as the "AbInitioProgram" in the Abins or Abins2D algorithm. This requires Mantid version 6.10 or later, or a Nightly build from April/May 2024.

Requirements

The script was developed with Python 3.10 and requires ASE; this is not included with Mantid so you may need to install it with pip install ase.

Limitations

• The correctness has not been fully verified yet against another calculation method. It appears that the eigenvectors are normalised correctly but validation is recommended before use in production.

• The Molden format does not include atomic masses, so we get the standard masses for each element (i.e. standard isotopic mixtures) using the ASE library.