first off, please always send a copy to the mailing list.
axel
There're some papers doing like that way to avoid gas molecule, like O2, N2, i just don't know how.
there is a difference between fending off gas molecules and
disallowing structures that are consistent with the potential.
but then again, you have the functional form, you have the
potential file, you have a text editor.
you can change the parameters any which way you want.
however, if you just want to add a repulsive term between specific
atoms, like in the example that you describe, i'd rather use
hybrid/overlay and then add a lennard-jones potential with the
cutoff set to the minimum and a suitable sigma. that would in
my opinion be a cleaner way to handle this.
but then again. it is all your choice.
axel.