New to Lammps and need some help. I am trying to set up an simulation with polymer melt confined between two flat walls (perpendicular to the z direction). Then I want to pull the upper wall at a constant velocity Vz and calculate the force needed. The script i used is something like:
fix 1 boundary setforce 0.0 0.0 0.0
velocity upper set 0 0 0.3 units box
velocity lower set 0 0 0 units box
Constant pull is achieved but the information of forces acting on the walls is lost since I set them to zero. Is there any way to retrieve the forces acting on the top wall before I set the force to zero since they should be calculated anyway by Lammps? Or is there any other way to move the wall ?
thanks a lot;