I’m using LAMMPS (7 Aug 2019).
I want to apply a shear stress, parallel to the top and bottom surfaces, to my system. To do so, according to posts, there are roughly methods:
- make the system non-periodic and deform the top and bottom layers of my system
- make the system non-periodic and apply velocities to the top and bottom layers
- make the system non-periodic and use ‘fix addforce’ to the top and bottom layers
Since I want to control the stress, I may try the third one. However, LAMMPS documentation states ‘fix addforce’ adds fx, fy, fz, to atoms, which seems to be normal forces. Then is there a way to apply the shear force?
I also tried another way. Keeping the system periodic along all the directions, use ‘fix npt’ to ramp up the shear stress. The simulation can run, but I’m not sure whether the results are physically meaningful or not. I need to check it.
Do you guys have any better ideas about this?