Dear LAMMPS users，
I want to simulate a system which consists of two parts: one is an infinite substrate with a finite hole, the other is the liquid that cover the substrate including the hole. Then I placed a wall/reflect above the liquid to prevent the atoms from escaping. What I want to do is to cool the system to observe the nucleation process. My question is what the boundaries in the x, y and z axes I should choose. The substrate is placed in the x-y plane and the axis of the hole is along the z direction. The liquid seems have two parts: one is on the surface, the other is in the hole, so it is not suitable to choose the periodic boundary condition for x-y plane. It will be much better to choose boundary conditions for two parts respectively, if possible. On the other hand, I want to choose fixed boundary for the z axis. I am not sure whether these choices are right.
Thank you for your help!