Read FAC atomic data

[cjperks7]

As you say adf04 isn't a special file type so I propose adding an option to use FAC atomic data in ColRadPy

FAC promises it can do everything. In particular, I'm paying attention to knowing how to make:

• Spontaneous emission rates
• 2-photon emission rates
• Collision excitation/de-excitation rate coefficients
• Radiative recombination rate coefficients
• Dielectronic recombination strengths (+autoionization rates)
• Collisional ionization (+innershell) rate coefficients

The FAC documentation seems suggest it can't do three-body recombination. Currently, I've been using a FAC-function that automatically convolutes cross-sections with a Maxwellian but can do an option for something more general.

I know how to read the FAC data files so I propose to do this.

Is there any hiccups you'd foresee? For the rate coefficients, I'd be giving it a function of Te in units [cm3/s]. Looking at the structure of colradpy.data['rates'] I'm not actually sure how to incorporate the autoionization rates. I'd guess I can just sum the spontaneous emission and 2-photon emission rates hopefully being aware of the different broadening.

FAC also gives cross-section data so I propose also including an electron energy distribution function (EEDF) convolution function in the event you didn't use FAC's tools to convolute a Maxwellian vs. Te. I'd guess it'd be reasonable to assume anyone interested in using this functionality know how to set the cross-section energy grid in FAC themselves so it can be assumed the given cross-section data is sufficient for the desired EEDF.

Thoughts on this?