[gmx-users] Constraints & Restraints

[darrellk at ece.ubc.ca]

Hi,
I just have a quick question on contraints and restraints. My
understanding is that "constraints" fix the position of an atom in
space and "restraints" restrain the deviation of the atom's position
from its equilibrium point. Is that correct? If so, then I am a little
confused by the purpose of "constraints = all-bonds" or "constraints
= none" in an mdp file, since by selection of a force field, which has
bond/angle/dihedral stretching/bending/torsion constants, we are
specifying the constraints applied to the simulation. So then what is
the purpose of "constraints = all-bonds" and "constraints = none"?

Thanks.

Darrell