[gmx-users] Using the Pull Code to Restrain an Ice Layer

[Daniel Kozuch]

Hello,

I am attempting to restrain an ice layer in a system with liquid water. I
initially considered using position restraints, but it seems like GROMACS
has a few quirks that make that difficult: you have to create a new .itp
and define the crystal water as different from the liquid water, then use
constraints instead of settle, etc.

So I was wondering, is there was a way to achieve this (restraint of the
ice layer) with the pull code? This would be extra helpful since I want to
use the free energy code also to slowly relax the restraint and allow the
ice to become liquid water. This requires the restraint of many atoms
though, not just one center of mass, so I don't know if this is possible.

Any suggestions are welcome, and apologies if this is a duplicate (I had
trouble with the mailing system).

Thanks,
Dan