[lammps-users] How to move grafted surface in grafted polymer brush simulation

Hi all,
  I am doing investigations on properties of polymer brush when two apposing grafted brush surface slide relatively. I don't know how treat real surface in molecular dynamics and avoid this problem by a method, which defines a hundred times attraction force between Wall(z=0) with grafting end monomers by wall LJ command than other monomer-monomer LJ12/6 potential. Because there is no real surface in my simulation. It looks impossible to slide one grafted brush surface. Could someone give me help or hint to do this project?
  I very appreciate help from all.

Best wishes,
Yangpeng Ou

I don't understand your model, but you can slide two
surfaces past each other by applying a force or velocity
in opposite ways to each of them.