I'm trying to use mmfp to "punch a hole" in a lipid bilyaer into which I want to place an ion channel. Is there some way I can use MMFP to force all atoms within a given cylinder out of that cylinder? I've tried the following code:

GEO cylinder -
xref 0.0 yref 0.0 zref 0.0 xdir 0.0 ydir 0.0 zdir 13.8 -
force 1000.0 droff 9.3 outside select type * end

But that just pushes everything into the cylinder. Thanks for your help.