Constraint or not turned off on slaves
If constaints where put on "none" in the mdp file:
Then in /mdlib/update.c :
/* if edyn->bEdsam == FALSE --- this has no effect */
bHaveConstr = bHaveConstr || ed_constraints(edyn);
returns FALSE on the master, but TRUE on the slaves.
This means that the constrainst loops become active on the slaves, which will
interfere with the dynamics.
When T-coupling is used, one temperature group can be both devided on the master
as on the slaves. The total mean temperature of the T-group will be the desired
temperature. However the desired maxwell distribution will be disrupted.
Actually for a homogenous LJ-system I found that the mean temperature on the
slaves is 30 K lower at the desired reference temperature of 300 K than on the
This Bug may have a significant effect on the users of GC-models.
I tested it for the version 3.3, but it may also be present in the older versions.