Regarding the issue of using fix wall/reflect in periodic boundary conditions

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Dear LAMMPS user
I encountered a problem while trying to replicate a simulation of a paper that used both periodic boundary conditions and fix wall/reflect. However, I saw in the LAMMPS manual that they cannot be used simultaneously. I’m not sure if the author used some methods that I’m not familiar with, but I would appreciate it if you were willing to communicate with me. The following is the source of the paper and the model used in the paper, which simulates the evaporation of SPC/E water molecules on the surface of liquid gallium.

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A molecular dynamic study of the boiling heat transfer on a liquid metal surface with different thicknesses - ScienceDirect

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The documentation says (fix wall/reflect command — LAMMPS documentation)

Any dimension (xyz) that has a reflecting wall must be non-periodic.

Periodicity is fine in dimensions that do not have walls. Try it for yourself: a simulation with

boundary p p f

should work fine with fix wall/reflect in the z dimensions.

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Thank you for your answer. I found that the kspace_madify command seems to be able to implement the setting in the paper, setting non periodicity in the z-direction.