README.rst

SEAMM Atomic Charges Plug-in

A SEAMM plug-in for computing atomic (partial) charges from a converged electron density.

• Free software: BSD-3-Clause
• Documentation: https://molssi-seamm.github.io/atomic_charges_step/index.html
• Code: https://github.com/molssi-seamm/atomic_charges_step

Features

This plug-in is a post-processing step: it runs after a quantum-chemistry step (VASP, Gaussian, Psi4, ORCA, …) that has produced an electron density, reads that density, and uses a real-space density-partitioning program to assign a partial charge to each atom. The charges are written back into the configuration as a labeled charge set (e.g. charges_DDEC6) so several schemes can coexist on the same structure.

Supported methods

• DDEC6 (via the Chargemol program) -- ESP-faithful, chemically transferable charges that work for molecular and periodic systems, including metals. The recommended general-purpose / force-field charge.
• Bader / QTAIM (via the Henkelman bader code) -- a rigorous topological partition of the density, the charge solid-state users expect.

Both consume a real-space density grid (or cube), so they apply equally to periodic and molecular calculations. They need the all-electron density from the upstream step (for VASP, CHGCAR plus AECCAR0/AECCAR2 via LAECHG=.TRUE.).

• Free software: BSD-3-Clause license
• Documentation: https://molssi-seamm.github.io/atomic_charges_step/index.html

Acknowledgements

Developed by the Molecular Sciences Software Institute (MolSSI), which receives funding from the National Science Foundation under award CHE-2136142.