[gmx-users] Restraining water

[Guido Polles]

Hi,
I know it looks a little bit strange, but i was trying to restrain
just some water in my system.
Now, if i put something like
[ position_restraints ]
;  i funct       fcx        fcy        fcz
   1    1       1000       1000       1000
I put restraints on all the molecules.
I thought about a turnaround,  just making a second water molecule
type, but now complains about using more than one settle type.
Is there any other way to do it?
And if I follow the "Suggestion: change the least use settle
constraints into 3 normal constraints" I have to worry about some kind
of huge loss in performance?
Thank you

Guido