BFrescox TYPE=0 template issue

[jared321]

Adapted from a conversation between Manuel and Kyle:

While benchmarking solvers against Bfrescox, Manuel noticed that currently the mass of both the target and projectile are passed into the template generator in the &POT TYPE=0 line. This means that Bfrescox is setting

• ap=mass_projectile and
• at=mass_target

in this line. Frescox scales interaction radii by ap^(1/3)+at^(1/3), which is as desired for ion scattering (ap > 1). However, it is likely a problem for users that use this template for nucleon scattering problems (ap = 1), which should typically scale only as at^(1/3). In this case, Frescox could be forced to scale as desired by setting ap = 0 in the NML input file. However, it might be necessary to confirm that such a setting does not result in unintended and undesirable side effects for the simulations.

To address this, we should

• update template generation so that it demands that the user choose either the Ap^(1/3) + At^(1/3) radii scaling or the At^(1/3) scaling and
• improve documentation to help users understand this potential difficulty and to help them use the template generation functionality correctly for their purposes.