Bugs fixed

Collective variables module (Colvars) update

The (Colvars) library for enhanced sampling simulations included in GROMACS has been updated to version 2025-10-13.

This update brings many fixes, including some errors in gradient calculations, mostly affecting rarely used cases (see this page for details). A complete list of changes can be found here.

Tpr-file versioning fixed

Older installed GROMACS versions are intended to be able to do at least basic reading of .tpr files written by newer versions of GROMACS, unless made impossible by changes to the .tpr format. This happened in GROMACS 2025, but was not accompanied an appropriate increment of the version numbers, resulting in incorrect and misleading error messages. This cannot be fixed retroactively for installed GROMACS versions and extant .tpr files, but at least the problem conditions will no longer continue to arise for newly created .tpr files.

Issue 5334

Fixed missing non-bonded interactions with direct halo communication

When using the experimental direct halo communication feature combined with 8-wide SIMD non-bonded kernels and OpenMP threading, non-bonded interactions could be missing.

Issue 5509

Allow atoms involved intermolecular-exclusion to be perturbed

Issue 5527

Added check for constructing atoms of virtual sites

Constructing atoms for virtual sites can themselves be virtual sites, but only when those constructing atoms are virtual sites are higher up in the function type list (i.e. simpler constructions). This was documented in the manual. Now``grompp`` and mdrun will throw an error when these restrictions are violated.

Issue 5535