[phenixbb] scattering factors

[Ralf W. Grosse-Kunstleve]

> Thanks for replying to me. I believe I have the 5 Gaussian
> approximation for the values of a1-a4, b1-b4, and c for electron
> scattering factors. I think this is the same format as in the
> International Table volume 4.

Yes, that sounds right.

> I haven't been able to locate a
> library file in phenix directory so I presume that the information
> is incorporated into the codes or in cctbx.

The coefficients are mostly pulled from various compiled-in tables
in cctbx/eltbx/xray_scattering, but sometimes from other sources.
We need to add new phenix.refine parameters that can be used to
override the table lookups. A good Python programmer could probably
insert shortcuts. Are you familiar with Python programming?

Ralf