I want to generate a set of interatomic potentials between 5 chains of a polymer. I have all the required parameters to calculate the force field, but I am unable to understand the format of representing the potentials.

For example : I have polyethylene, the interactions are C-C H-H and C-H.

Do all the C-C interactions come first, followed by the others, or do i arrange the interatomic potentials in an ascending order irrespective of the interaction type.

Any help would be much appreciated!

P.S: I need interatomic potentials for LAMMPS simulation.