GROMACS 2021.7 release notes

This version was released on January 31st, 2023. These release notes document the changes that have taken place in GROMACS since the previous 2021.6 version, to fix known issues. It also incorporates all fixes made in version 2020.7 and earlier, which you can find described in the Release notes.

Fixes where mdrun could behave incorrectly

Add missing net charge term when running PME on a GPU

When PME was running on a GPU, the term due to a net charge of the system was missing. In normal runs this only changed the potential energy by a constant, which is usually not relevant. In free-energy calculations where the net charge of the systen changes, the would lead to incorrect dV/dlambda and Delta lambda values (but one should anyhow avoid changing the net charge of a system with free-energy calculations).

Issue 4668

Fixes for gmx tools

Fixes that affect portability