Simulating isotropic biradical spectra

[katarkon]

Good day.
I try to simulate isotropic spectrum having two equal radical centres with hyperfine splitting on one 55Mn and one 1H nuclei. The J (ee-coupling constant) should be comparable with aMn. However, the function pepper gives equal results relativeless of the J value.
clear, clf
aH=mt2mhz(2.5/10);
aMn=mt2mhz(7.0/10);
J=aMn*[1e-4 0.01 0.3 0.5 0.9 1.5 2 2.5 3.5 5 7 9 12 20 40 1000];

Exp.mwFreq =9.663;
Exp.Range = [342 347];
Sys.S = [1/2 1/2];
Sys.Nucs='55Mn,1H';
Sys.A=[aMn aMn;aH aH];
Sys.g = [2.0030; 2.0030];
Sys.lw = [0 0.02];

Exp.nPoints=65536;

Opt.Method='matrix';

Opt.Verbosity=0;
for i=1:numel(J)
Sys.J=J(i);
[x,y1(i,:)]=pepper(Sys,Exp,Opt);
end
stackplot(x,y1,1,1);


[thanasis]

Just a suggestion: try introducing an asymmetry to your system, e.g. by varying one of the two g values.

What does that give?

[katarkon]

Thansk. I've found the solution. It looks that all of the spins should be included in the spin system. The right code will be as follows:
Sys.S = [1/2 1/2];
Sys.Nucs='55Mn,55Mn,1H,1H';
Sys.A=[aMn 0; 0 aMn; aH 0; 0 aH];
It seems to work fine.