weak interaction in polymetallic system

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yvesjour
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Posts: 10
Joined: Tue Mar 31, 2015 4:45 am

weak interaction in polymetallic system

Post by yvesjour »

My problem is to fit the EPR spectra that can be modelled as two weakly coupled S=3/2 system. The interaction between the two S=3/2 states is not measurable by magnetic measurement and I hope that I can determine the coupling by the evolution of the EPR spectra with temperature. But I found no example in the forum of this type of simulation.
How do I have to modify the following code to include in the fitting one or two other spectra of the same compound but recorded at different temperatures

Code: Select all

 % System with two  S=3/2, 
 
 clear
 light=physconst('LightSpeed')
 
[B,spc]=textread('/Users/yves/ownCloud/EPR.EasySpin/MATLAB.travail/RPE02.10.18_Ang/Cu2Ni4mpba.4K.txt','%f, %f');
 
Sys.S = [3/2,3/2];
 
gx=2.25 % fit magnÈtisme
gy=2.25
gz=2.08
 
Sys.g = [gx gy gz;gx gy gz];
 
 
J_cm=0.
JMHz = J_cm*100*light/1e6
 
Sys.J = [JMHz]
 
D_cm=3.5
E_cm=1.
DMHz=D_cm*100*light/1e6
EMHz=E_cm*100*light/1e6
 
Sys.D=[DMHz EMHz;DMHz EMHz]
 
 
Sys.HStrain = [700. 700. 6000.]
 
 
Exp.Range = [2 1000];
Exp.mwFreq = 9.344108139;
Exp.Temperature=4.

SimOpt.nKnots = 35;
 
Sys0 = Sys;
Sys0.D = Sys.D;
Sys0.HStrain=Sys.HStrain
Sys0.g=Sys.g
Sys0.J=Sys.J
 
SimOpt.Method = 'Matrix';
 
Vary.D = [1e03 100]
Vary.J=[1e03]
Vary.HStrain = [10 10 50];
Vary.g=[.05 .05]
 
%FitOpt.Method = 'simplex';
FitOpt.Method = 'genetic';
FitOpt.Scaling = 'maxabs';
 
esfit('pepper',spc,Sys,Vary,Exp,SimOpt,FitOpt)
 
[H, I]= pepper(Sys, Exp, SimOpt);
 
plot(H, I*1000,'r',B,spc,'b');
thanasis
Local Expert
Posts: 252
Joined: Thu Jan 21, 2016 6:28 am
Location: Strasbourg

Re: weak interaction in polymetallic system

Post by thanasis »

You will need to write a custom function.

I have been greatly helped by the example http://easyspin.org/easyspin/examples/f ... ultifreq.m and by the thread viewtopic.php?f=3&t=211 in doing multispectra simultaneous fits. Once you set it up, you can then do multi-frequency, multi-T, multi-angle (for single crystals), etc... simultaneous fits in the same fitting window using the same set of spin Hamiltonian parameters.
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