Christina -
I think the problem is you are not specifying the potential for
the metal vs other types. i.e. i-j interactions when i .ne. j
In a hybrid simulation, LAMMPS will do this automatically via mixing
when types i,j are both for the same pair_style. But you need to do
it explicitly for the hybrid interactions. In your case types 38,39
are metal and the rest are lj/charmm/coul/long. So you need to
specify what style and what coeffs to use for interactions between
38,39 and the other types. E.g.
pair_coeff 137 3839 lj/charmm/coul/long 0.046 0.4000135 0.046 0.4000135
pair_coeff 3839 4041 lj/charmm/coul/long 0.046 0.4000135 0.046 0.4000135
(if that’s what you want for the coeffs)
Steve