[gmx-users] dummy atom - regd

[Bogdan Costescu]

On Mon, Feb 18, 2013 at 12:10 PM, Mark Abraham <mark.j.abraham at gmail.com> wrote:
> b) a particle needs to be at that immobile reference point - you can
> measure a distance to a point whether or not there is something there.

I'm not sure that it's the same use-case... I recently talked to
someone trying to define such a fixed particle to be used as a pull
group.  This pull group could then be set as reference in the middle
of the PBC box, such that the pull distances are smaller than half the
box size. The fact that the particle is really fixed when the PBC box
is allowed to change dimensions is not a big problem, if needed the
size of the box for each trajectory frame can then be used to correct
distances. I don't know what was the outcome, but I'm curious to see
such a setup.

Cheers,
Bogdan