EasySpin forum

The 59Co nucleus has a spin I=7/2, so it should give 8 lines with equal intensities due to HFC interactions.

You try to use diffrenent parameter's set for custom simulation function and esfit(). I mean Opt parameter.

You are wrong. According to the publication, you should use the S=1 approach instead of two coupled S1=1/2 and S2=1/2 spins.

Look here for the typo
Sys1;J = 0;

Sys.gFrame = [0 10 0; 23 -45 67]*pi/180; % two electron spins

The code seems to be right. But Sys.gFrame seems to be a better way. Also, there are no need to define full matrix for g-tensor, the principal values should be enough.

In GUI mode You have to save and export the parameters, Save parameters set --> export, see GUI window. The structure fit1 will be exported in the MATLAB workspace. The field fit1.fit contains required data.

Use 1H nuclei only, drop down 13C ones and define the spin system correctly.
Sys.S = [1/2 1/2];
Sys.Nucs='1H,1H';
Sys.A=mt2mhz([aH 0.0;0 aH]/10);