Epr data fitting for Fe(III) S=1/2 and S=5/2 using pepper

[bijoydey03]

Dear all,
I have been trying to fit the epr data for a Fe(III) low spin system with S = ½ but unable to fit the data properly. I have used the attached input file, please have a look at the input for any mistake or suggestions. The spectra corresponds to a axially distorted environment so I used (gx=gy≠gz). What should be the RMSD value for the fitting to be acceptable for publication. I have provided the fitting parameters also, please have a look.
Similarly another Fe(III) in low spin state has been fitted with the isotropic model but when it converted to high spin state having S = 5/2 epr spectra could not be fitted. The Hamiltonian for a high spin Fe(III) is as follows
H = gβBS + D[Sz2-1/3S(S+1)] + E(Sx2-Sy2)
But I am not getting how to include D and E parameters in fitting. I fitted the data considering the isotropic model.
It will be very helpful if anyone can suggest how I can fit the high spin data. Can the data be fitted considering both low spin and high spin systems as the system is neither fully low spin or fully high spin system.
Thank you to all

[Stefan Stoll]

For the S=1/2 fittings, it looks like you just haven't localized a good minimum yet. Apart from the unconverged parameters, the models look reasonable. For the high-spin system, use Sys.D to incorporate D and E.

[b6036442]

Hi,
I have a very basic doubt. Once we have g values from experimental and simulation data, what all information we can have about the structure and how can we obtain this information?

[Stefan Stoll]

This is a question beyond EasySpin. Please refer to textbooks on EPR for this.