[gmx-users] translation of the system - regd

[ramesh cheerla]

Dear Gromacs  uses,

                  I have  freezed  one of the non-bonded atoms in my
simulations, which is a part of the system. when visualizing  the
trajectory have observed that the freezed atom is not moving but the
remaining system as a whole translating with respect to the  freezed atom
along one particular axis though I  have removed the center of mass motion
for the whole system.
 I have used  following options  in my .mdp file to freez and remove center
of mass  motion

comm_mode       = Linear
comm_grps       = System
freezegrps = PEGR
freezedim  = Y Y Y
energygrps=system1 PEGR
energygrp_excl=system1 PEGR

Here (System=system1+PEGR)

Can anybody suggest me the reason for the translation of the remaining
system when compared to freezed atom.

Thank you in advance,

Regards,
Ramesh.