Hi - I’d like to run a bulk solid (periodic, fully connected across all the boundary conditions) with only a bonded potential (specifically bond_style class2). I haven’t been able to find any unambiguous statement about whether this is possible. I’ve discovered that I have to do a
comm_modify mode single cutoff CUTOFF
to get things to work at all. Is it true that given the cutoff, LAMMPS will use minimum image convention to determine the relative position vector of each bonded pair? Is there anything else I need to do?
it might be more straightforward to use pair style zero. you can set a cutoff just with any other pair style but it will not do any computations.
LAMMPS does NOT use minimum image conventions. bonds are defined with the “closest” atom in the respective sub-domain. increasing the communication cutoff (or the pair cutoff) will make sure there are a sufficient amount of ghost atoms so that the closest atom for bonds across periodic boundaries is the ghost atom on the “same side” of the box and not one somewhere else (or you would get a bond atom missing error when running in parallel).
Thanks. So if I set a pair_style zero, that means I don’t have to do a comm_modify, right?
Correct, but you will get neighbor lists. If you don’t need them, then it’s cheaper to
not define a pair style at all.
See the pair zero doc page.