Hello, everyone!
I have a question about simulating the EPR spectrum of a cluster containing more than 100 equivalent magnetic nuclei (I = 3/2). The anisotropic g-value for S=1/2 was derived from the spectrum. How to add the hyperfine coupling constants of these magnetic nuclei? When I use the pepper function, only a few nuclei are able to be accounted for the hyperfine splitting by nucspinadd. How to extend these to 150 atoms, for example?
thanks for the help!
In a simulation sense, the only way you could reasonably simulate such large number of nuclei would be switching the method to use perturbation theory, Opt.Method = 'perturb', 'perturb1' or 'perturb2'.
From a practical standpoint, unless you can see structure in your EPR spectrum, 100 equivalent nuclei are likely just lost to the inhomogeneous line broadening. The line broadening can probably be used to derive a relationship for the hyperfine given the number of nuclei or vice versa. Such as https://doi.org/10.1073/pnas.68.3.625
A cluster with 100 equivalent magnetic spin-3/2 nuclei sounds quite intriguing - I wonder what the chemical structure is.
Unless your EPR spectrum shows resolved splittings from all these hyperfine couplings, it's probably better to just use Sys.HStrain to model the resulting anisotropic unresolved cumulative line broadening.
Also, you might be pushing the limits of EasySpin (more specifically, your computer memory) when trying to simulate a spectrum from a spin system with more than a dozen or two or so nuclei, even with perturbation theory.