“An alternative slab option can be invoked with the nozforce keyword in lieu of the volfactor. This turns off all kspace forces in the z direction.”
I am wondering if there’s any reference for the choice of kspace_modify with slab nozforce, instead of using a value of volfactor, say 3.0, as usually done in the literature.
I don’t think there is a reference, but I recall a discussion on this mailing list about that subject and if I remember correctly, that prompted the implementation of the flag. So digging through the mailing list archives might provide an answer, why this was needed and what it was used for.
I believe the original purpose of “slab nozforce” was to couple to another code/package that provided this force instead of LAMMPS KSpace. Like USER-ATC or something like that, I don’t recall 100%.