SEAMM Set Cell Plug-in

A SEAMM plug-in for Set Cell

• Free software: BSD-3-Clause

• Documentation: https://molssi-seamm.github.io/set_cell_step/index.html

• Code: https://github.com/molssi-seamm/set_cell_step

History

2026.10.17 – Set the cell to the mean volume of an NPT run, moving molecules rigidly

• A new way to set the cell: the mean volume of the last NPT run earlier in the flowchart, over its equilibrated part – the usual preparation of constant-volume runs of a liquid at its equilibrium density. Setting a density or a volume, including from a variable, works as before.

• A new option, how the contents follow the cell: the molecules moved rigidly with their centers, so their bonds are unchanged, or the atoms scaled with the cell. By default the molecules for a system of separate molecules and the atoms for a solid or an extended network. Before, the atoms were scaled, which stretched the bonds of every molecule; a rigid water model could then fail in its first step.

• Bugfix: “uniform contraction/expansion” with a percentage (the default, “1%”) failed.

• The volume, density and cell parameters are results, for variables and tables.

• Internal: the package, its tests, documentation and CI are brought up to date (Python 3.12, current SEAMM).