Stefan Stoll wrote:ES does not have much built-in functionality for spin-polarized radical pairs. Maybe worthwhile considering.
Once I sorted out this business with fitting the triplet and quartet I was going to begin playing around with ES and see about trying to fit some radical pair spectra I've collected.
Have you tried to simulate a spectrum without polarization using Opt.Output = 'separate' (returns each transition separately) and then linearly combining the transitions with the emissive or absorptive prefactors for your particular case?
I had considered that, though I really wanted to see if I could do the fitting completely within ES and using esfit, and this whole discussion came out of my confusion in the polarization patterns. For the time being I'll write a wrapper for EasySpin to do what I need.