Revisit screening prescriptions to include electron-ion polarization effects

[jschwab]

While working on "screening" (electron-ion polarization effects) in the EOS, A. Y. Potekhin made the following comments on the nuclear reactions screening in MESA:

the prescriptions by Chugunov et al. (2007) for screening of nuclear reactions ignore the electron-ion polarization and therefore are not very accurate. For the classical nuclei, the old prescription by Salpeter & van Horn (1969) is even better. A more accurate prescription, which takes into account the polarization and also matches the Chugunov et al.'s results for strong quantum limit, is that of our paper with Gilles Chabrier, A&A 538, A115 (2012).

This might be useful info in future work on screening, so noting it here.

[rjfarmer]

https://ui.adsabs.harvard.edu/abs/2012A%26A...538A.115P/abstract

Looks like we'd still pick up a cube root-or-two, so mesa will still be a logarithm solver.