[lammps-users] problem with the relax

Thanks! When the pbc is used, the tested result is right, and the
only difference between them is the calculation of the coulomb
interaction, so I think this is the problem. Although the model will

no this is _not_ correct. with shrink wrapped boundaries,
you do _not_ have periodicity, i.e. you take away _all_
interactions with periodic images. you have effectively
converted a chunk in the middle of a crystal into an
isolated cluster. thus atoms near the surface of the
simulation cell are no longer confined and can expand.

expand when the boundary is free, but in this case, I think the final
model is compelely unavailable, its size is too large. Maybe the
potential parameters are only suitable for the pbc model, I think!

no. there are no pbc only classical potentials.

Any idea?

i have to repeat myself: this is a question you have
to ask yourself! why do you expect that when you change
from periodic boundaries to shrinkwrap that the system
cell size should remain the same? there is no good reason
for it... at all. even a block of the hardest solid will
expand if you remove periodicity.

as i wrote before, the problem exists between the chair
and the computer and not within.