Using kspace_modify slab for a triclinic crystal

Dear LAMMPS users,

I plan to study the cohesive energy or lattice binding energy of a crystal
as a function of increasing layer in the a, b, and c direction in an NPT simulation.
I’ve considered using the “kspace_modify slab” option; however, my understanding
is that one cannot use the ewald/n solver (for non-orthogonal simulation boxes) in
conjunction w/ a triclinic crystal whose xy, xz, and yz tilt factors are all non-zero.
The “boundary p p f” setting would conflict w/ having a non-zero tilt factor in xz
and yz (as the z-direction is non-periodic). Does this also mean that one can only
use the ewald/n solver w/ a monoclinic simulation box whose orientation leads to
xz and yz being zero and only xy being non-zero (as the x- and y-directions are

I appreciate any confirmation/clarification or fixes on this matter as well as any
advice for an alternative approach to study the problem described above.


You are asking several questions. Here are some details.
Ask again if this is not sufficient info.

PPPM cannot be used with triclinic boxes. Ewald/n can.
Kspace modify slab only makes sense for systems that
are not periodic in z, so that is not compatible with any
triclinic boxes that are peroidic in z. In triclinic mode
that would only allow for an xy tilt, since xz and yz require
periodicity in z.