Thank you very much for your detailed explanations Dr. Kohlymeyer, I will
work on force field parameterization strategies, partial charges of BN and

for starters you should read the two papers i referenced and the
material they reference.

try to modify the model with your suggestions if this ONIOM approach is
applicable in Lammps?

not quite. i have a QM/MM code that would do the BN part via ONIOM
with density functional theory instead. however, there should be no
technical problem to extend this to make this an MM/MM coupling. the
major obstacle is that i don't have the time to do it myself right

for testing purposes, you could use lj/cut/coul/cut instead of lj/cut/coul/log

an alternative of an explicit ONIOM implementation would be to
subtract out coulomb from the two-body interactions in your tersoff
model ahead of time and then your pair style hybrid/overlay with
coul/long for all atoms, the modified tersoff for B-B, B-N, and N-N,
and lj/cut for O-O, O-B, O-N, H-B, H-N

not perfect either, but a bit better than having no long-range coulomb.

you also could use the proposed LJ based models form one of those papers.