In my LAMMPS simulations, I am using non-periodic boundary conditions (s) along one axis (for example, the z-direction). However, during the relaxation simulation run, I observe that the box length in this non-periodic direction changes or expands with time, even though I want the dimension to remain fixed.
I understand that this behavior can occur due to thermal expansion, applied forces, or the use of certain fixes (e.g., fix nvt, pressure coupling, or atom loss at free surfaces). However, for my case, I want to strictly keep the box dimension constant in the non-periodic direction while still allowing atoms to move naturally.
Could anyone suggest me is there any way to fixed this problem?
When posting in a public forum, you should make certain that you post to the correct category.
Questions about LAMMPS should go to one of the LAMMPS categories. Your post has nothing to do with the Materials Project. I have noticed your post by accident and will this time send it to the proper category, but don’t expect that to happen in the future.
This is the documented behavior!
The “s” stands for “shrink-wrap” boundary conditions, i.e. the box dimensions follow the extent of the particles in that dimension.
Your understanding is not quite correct.
So you should use “f” instead of “s”. Just check the documentation!