[lammps-users] tersoff potential problem

You can't do this with the hybrid potentials as they are currently
setup in LAMMPS. You could specify C C C C for types 1-4 with
the pair_coeff command which would do what you want except
that you will also get Tersoff interactions between the 2 CNT,
assuming they are close enough to be within cutoffs. You could
also superpose on top of this (via hybrid/overlay) some additional
pair potential for interactions between atoms in 2 different CNT (e.g. LJ).

Physically, I can't imagine a potential (like Tersoff) that interacts
only between atoms in one CNT but magically ignores nearby C atoms
that are in another CNT. That's not what a bond-order potential
like Tersoff means conceptually.


Another thought. You might be able to do what you
want using

pair_coeff * * ... C C C C

and neigh_modify exclude to turn-off cross interactions between
atoms in the 2 molecules (either by group or type). If no
pair interactions for I,J are in the neighbor list where I is in one
CNT and J is in the other, then I think Tersoff will do what
you want.

I emphasize again that this is an odd model.