# GROMACS 2019.4 release notes¶

This version was released on TODO, 2019. These release notes document the changes that have taken place in GROMACS since the previous 2019.3 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 incorrect pressure when atoms in CMAP cross a box boundary¶

The virial calculation and thus the pressure would be incorrect when the second and third atom involved in a CHARMM CMAP correction term would reside in different periodic images. This can happen when a protein is positioned over a box boundary. Note that the energy and forces were correct, but sampling was affected when pressure coupling was applied when a protein crossed a box boundary.

### Fix incorrect LJ cut-off on GPU when rvdw < rcoulomb¶

When rvdw was chosen by the user to be smaller than rcoulomb in the mdp file, the LJ cut-off would initially be set to the Coulomb cut-off for computing non-bonded interactions on the GPU. This only affected energy minimization, mdrun -rerun and the first 2*nstlist steps of a normal MD run, since the correct LJ cut-off is set when PME tuning (on by default) starts after 2*nstlist steps (unless PME tuning was disabled with -notunepme).

Issue 3056

### Fix (unlikely) missing bonded forces with CUDA GPUs and domain decomposition¶

Forces could be missing for bonded interactions computed on CUDA GPUs with domain decomposition when there are non-local bonded interactions, but no non-local non-bonded interactions between two domains. Note that this is extremely unlikely to happen, since the distance between the bonded atoms needs to be larger than the pair-list cut-off distance and there should be no other non-local atoms within the pair-list cut-off distance.

Issue 3063

Issue 3023

## Fixes for gmx tools¶

### Fix grompp not adding angle constraints between constraints¶

When using the mdp option constraints=all-angles, angles involving bonds supplied as constraints in the topology would be removed, but not replaced by angle constraints.

Issue 3067

### Fix bug in gmx xpm2ps¶

The tool would fail when not being provided with a library file to read in.

Issue 3012

### Fix bug in gmx anaeig¶

An issue was noted when reading a second set set of eigenvectors that could lead to problems when the number of eigenvectors was less than the three times the number of atoms.

Issue 2972

### Fix issue with demux.pl script¶

The trajectories could become discontinuous with simulations longer than 100ns and exchange strides that are not a multiple of 1 ps. This only affected the post-processing of trajectories generated from replica exchange simulations.

Issue 2953

## Fixes that affect portability¶

### Disable PME OpenCL on Apple¶

The Apple OpenCL compilers fail to produce a functional clFFT build. The OpenCL PME support is therefore disabled on Apple platforms.

Issue 2941