I'm trying to simulate the hyperfine resolved EPR spectrum for coupled Donor (D)-Acceptor(A) radical pairs (D and A at distance of 12.4 angstroms distance). The following code has been used. Can someone point out how to modify the following code, to couple the two radical spins? Also, can anyone explain to me how the coupled and uncoupled radical spins affect the EPR hyperfine splitting pattern?
Code: Select all
clear
%Experimental spectrum
[B,spc] = eprload('TAN_LNT');
%Spin A:
SysA.S = 1/2;
SysA.g = [2.009048];
SysA.Nucs = '1H,1H,1H,1H,1H,1H';
SysB.weight = 1;
SysA.A = mt2mhz([15,15,15,3.5,15,15]/10);
SysA.lwpp = [1.2];
VaryA.g = [0.1];
VaryA.A = mt2mhz([1,1,1,1,1,1]/10);
VaryA.lwpp = 0.15;
VaryA.weight = 0.3;
%Spin B:
SysB.S = 1/2;
SysB.g = [2.0095];
SysB.Nucs = '14N';
SysB.weight = 01;
SysB.A = mt2mhz([7.1]/10);
SysB.lwpp = [1.1];
VaryB.g = [0.1];
VaryB.A = mt2mhz([1]/10);
VaryB.lwpp = 0.2500;
VaryB.weight = 0.3;
%Defining the two spins together:
Sys = {SysA SysB};
Vary = {VaryA VaryB};
%Experimental details:
Exp.mwFreq = 9.141295;
Exp.Range = [309.9668 339.872];
Exp.nPoints = 65329;
Exp.ModAmp = mhz2mt(0.1); %in mT
Exp.Temperature = 80; %in Kelvin
Exp.Mode = 'perpendicular';
B = linspace(Exp.Range(1),Exp.Range(2),Exp.nPoints); % field axis
%Next, we specify which parameter we want to be fitted
% and by how much the fitting algorithm can vary it approximately.
% Calling the fitting function
SimOpt.Method = 'perturb';
FitOpt.Method = 'simplex fcn'; % simplex algorithm, integrals of spectra
[fitparams,spc] = esfit('pepper',spc,Sys,Vary,Exp,SimOpt,FitOpt);
hold on;
%Loading experimental spectrum.
data=textread('TAN_LNT.dat');
x=data(:,1);
y=data(:,2);
plot(x,y,'b');
%Saving in ascii format
data = [B(:) spc(:)];
save('TAN_LNT_sim.txt','data','-ascii');
plot(B,spc,'r');
hold off;