How to choose a appropriate boundary ?

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!


Xiaodong Su

The boundary command is for the entire simulation box, not

parts of your model. Just use non-periodic in z, either fixed

or shrink-wrapped.