particles in or on fix wall surface during indentation


I have a membrane that is adhered to a rigid surface (fix wall LJ/93) and using the command “indent” I apply a normal load, and then set the spherical indenter to sliding (think rigid AFM tip). The tip slides for a while, but eventually I get the error: “Particle on or in fix wall surface”, which seems a bit unusual since the indenter is sliding laterally along the membrane and not pushing atoms further down to cross the fix wall surface.

Is there a way to prevent this from occurring or to prevent the code from crashing when this happens?


The fix wall command is doing a very simple check, as discussed
on its doc page. No particle can be (exactly) on the wall surface
or inside the wall. This is b/c the formula blows up to infinite
energy if that is the case. So however you move the walls
and nearby particles, you need to prevent that from happening.