Enforce that `Z_1`, `Z_2`, `mu`, `eta`, `k`, and `E` are specified similar to parameters

[beykyle]

There is no reason for a specific Interaction to be hard-coded for a single isotope and energy. One should be able to build a High-Fidelity solver that works across isotopes and energies.

I think just concatenating these things onto the interaction params would be the way to go:

Z1, Z2, mu, eta, k, E, params = alpha

and params is passed into Interaction.v_r, for example.