[gmx-developers] distance restraints and domain decomposition

[Kutzner, Carsten]

Dear developers,

we have a ~ 40,000 atom MD system with distance restraints (bond type 6)
that does not want to run in parallel, although I assume it should.
It runs fine without DD, e.g. -ntmpi 1 -ntomp 20, however with DD the
following happens:

mdrun -ntmpi 2

Fatal error:
There is no domain decomposition for 2 ranks that is compatible with the given
box and a minimum cell size of 11.4939 nm

The maximum distance restraint distance is however at 4.0 nm, so 11.49 nm as
reported cannot be true, unless the PBC distance is not taken properly
into account. Is this the expected behaviour or worth generating a redmine
issue?

Thanks,
 Carsten