I think that's all that it's been used for, i.e. FENE chains.
However, I don't see a reason we couldn't allow sigma/epsilon to be specified
(optionally) as part of the bond coeff command. In which case you would
have to carefully choose all the other params, as it describes in the doc
When monomers with sigma = epsilon = 1.0 are used, the following choice of parameters gives a quartic potential that looks nearly like the FENE potential: K = 1200, B1 = -0.55, B2 = 0.25, Rc = 1.3, and U0 = 34.6878. Different parameters can be specified using the bond_coeff command, but you will need to choose them carefully so they form a suitable bond potential.
to end with something that worked.