[gmx-users] pbc with nwall = 1

[toma0052 at umn.edu]

Hello,
     I want to study polymer adsorption onto a surface. To do so, I create 
a polymer-solvent system with a wall at z = 0 and use pbc = xy. This, 
however makes the system infinite in the z-direction. I was wondering if 
there was a way to create a periodic boundary at z = L such that when an 
atom crosses z = L the z-coordinate shifts to z = L/2 (rather than z=0 in 
normal pbc) but not the other way around. In this way I could have a 
portion of my system near the surface and a portion far from the surface 
which would represent the bulk. Is this possible? Would it require 
substantial modification to the code?

Thanks,
Mike