[lammps-users] fix wall/piston command and Long-range electrostatic interactions

Hello All,

I am using the Shock package in order to simulate a shockwave on water.

I am using SPC/E model for water and fix wall/piston command. One requirement for fix wall/piston is to use non-periodic boundary conditions in z direction, S (shrink-wrapping):

fix 1 all nve

fix walls all wall/piston zlo pos 0.0 vel 0.0 units box

velocity all set 0.0 0.0 -0.01 sum no units box

However the issue I have faced is to how calculate the long-range electrostatic interactions in z direction using pppm given the boundary must be s. I also cannot use kspace_modify slab to fix this.

My question was how to include long-range electrostatic interactions when using fix wall/piston command and non-periodic conditions in z?

Thank you,

Currently the only way to do long-range electrostatics for such a setup would be to use the MSM long-range solver. Unfortunately the MSM solver is not quite as “automatic” as the PPPM or Ewald solvers. So it needs to be carefully benchmarked with “static” calculations against PPPM to find the settings where you obtain sufficiently accurate results.