Kspace slab correction with compute group/group

Dear Lammps-users,

I want to do the MD of waters confined by non-uniformly charged surfaces, I’m interested in the force between water molecules and one surface, the commands are:


kspace_style ewald 1.0e-4

kspace_modify slab 3.0


compute Force spce group/group topsurface kspace yes


But Lammps reports :

ERROR: Cannot (yet) use Kspace slab correction with compute group/group (ewald.cpp:991),

I also tried to use 3D ewald directly assuming a periodicity in the z direction

with a simulation box size of 10 times of the distance between the surfaces. It does not work well.

Is there any other way to compute the force in Lammps? All suggestions are welcomed.

Thank you very much,


Stan can comment.