Dear DongSheng,
You can use what I suggested. Now, in lammps you can use two or more pair_styles on the same pair interactions. (See hybrid/overlay)…
That way, u can use
“pair_style hybrid lj/class2 10.0 lj/cut/coul/debye 0.01 2.5 25.0”
Here make sure that lj.cut epsilon is 0. So you can calculate vdwl interactions based on class 2 and electrostatic using debye for the same atomic pairs…
I hope this helps.
Regards,
Vikas