# GROMACS 2019.3 release notes¶

This version was released on June 14, 2019. These release notes document the changes that have taken place in GROMACS since the previous 2019.2 version, to fix known issues. It also incorporates all fixes made in version 2018.7 and earlier, which you can find described in the Release notes.

## Fixes where mdrun could behave incorrectly¶

### Fix missing interactions with domain decomposition¶

When running with domain decomposition, any interactions described by the rarely-used topology file section [ intermolecular_interactions ] were ignored. This did not affect normal non-bonded or intra-molecular interactions.

Issue 2953

### Fix possible floating point exception during minimization.¶

It was possible that very small forces during minimization could lead to a crash due to a divide by zero error. Fixed by introducing a check.

Issue 2917

Issue 2947

### Allow AWH with pull-geometry ‘direction’ to be periodic¶

When applying AWH to a pull coordinate with geometry ‘direction’ with a AWH interval length of more than 95% of the box size, the dimension is now made periodic.

Issue 2946

## Fixes for gmx tools¶

Issue 2951

### Fix PQR formatting¶

The formatting was incorrect for some tools that use PQR files.

Issue 2955

### Fix gmx wham with angle geometries¶

gmx wham would mix up degree and radian units leading to no overlap or not-a-number output. Note: this fix is not correct, a correct fix is applied in the next patch release.

### Give meaningful error with too large grid in hbond¶

When using a grid that is too large hbond could try to allocate enough memory to cause a crash.

Issue 2962

Issue 2911

## Fixes that affect portability¶

### Fixed wider reference SIMD setups¶

The reference SIMD builds could use a too small memory alignment, leading to mdrun exiting with an alignment error

Issue 2952

### Fixed build failure with Apple Clang¶

Builds would fail because of qsort being undefined.

Issue 2940

Issue 2932