incorrect volume with MTTK + particle decompostion
In version 4.5 running MTTK pressure coupling with particle decomposition give a too large volume. The error seems to roughly scale with the number of nodes. With domain decomposition it is correct.
In 4.6 I can't reproduce this, so it seems to be fixed.
We should find and backport this fix to 4.5, or disable MTTK with particle decomposition.
Some changes for md-vv extracted from 4.6a. Fixes for the pressure in MTTK with constraints + dispersion + rerun
- Dispersion is correctly added in rerun
- COM motion is removed only on the second half of the timestep.
- Now can do md-vv + rerun with multiple threads.
- Now gives exact kinetic energy reruns for everything except MTTK, where the iterative algorithm
makes exact kinetic energy impossible when nstpcouple == 1.
b. md-vv works with v-rescale and berendsen
c. Fixes a bug when pressure control in md-vv when nstcalcenergy is not a
multiple of nstpcouple or nsttcouple. This bug results in boxes slowly
expanding to unphysical sizes because the virial is
neglected in the second half of the md-vv calculation.
Also discovered that as part of the bug, global energies were being communicated
where they did not need to be when nstpcouple and nsttcouple are > 1 in the case
of md-vv, so redid some of the iteration counting and global communication to fix
this all together. In the process, this simplified some of the iteration counting.