[feature] Investigate LAMMPS interaction potential input files as option for interaction potentials

[drobnyjt]

Is your feature request related to a problem? Please describe.
Currently, new interaction potentials must be hard-coded, which is inconvenient.

Proposed solution
Investigate using the interaction potential file format from LAMMPS instead.

Alternative solution(s)
Figure out another text-based way of adding piecewise interaction potentials, functional interaction potentials, etc.