[gmx-users] Position restraints on a lipid bilayer

[toma0052]

Hello,
     I am looking to add position restraints to some atoms of a lipid
bilayer.  There seem to be a lot in the list archives on this subject, but I
am still a tad confused.  What I would like to do is to position restrain the
phosphorus atoms in only one leaflet of the bilayer.  So how do I generate
such a pr file, and where should I include it?  It seems as if things are
done per molecule, so if I put it in my *.top or *.itp files, the restraint
is on all P atoms in the system, not just the ones I want.  Is there a way to
do this so that things are indexed per atom rather than per molecule?

Thanks,
Mike