atomic-charges-step 2026.6.27.1

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

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.

History

0.1.0 (unreleased)

• Initial scaffold of the Atomic Charges step.

• Plug-in structure, parameters, metadata, Tk GUI, and installer in place.

• DDEC6 (Chargemol) and Bader (Henkelman) backends sketched; density handoff from the upstream QM step and the per-program output parsing are the remaining integration work.