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Posted: **Thu Jan 28, 2016 4:31 am**

Dear all,
I'm trying to simulate the experimental EPR spectrum for a donor-acceptor radical pair (D.+ and A.-) system. I started with garlic for the simulation with the following matlab code

g1 = 2.012; g2 = 2.0023;
A1 = mt2mhz([16.9,10.9]/10); A2 = mt2mhz(9/10);
Sys.A = struct('S1',1/2,'Nucs','1H,1H','g',g1,'A',A1);
Sys.B = struct('S2',1/2,'Nucs','1H','g',g2,'A',A2);
Sys.tcorr = 1e-9;
Exp = struct('Range',[310, 340],'mwFreq',9.137,'lwpp',0.55,'npoints',64293);
garlic(Sys,Exp);

Is there anything fundamentally wrong with the code that it is giving me the error as:

Error in garlic (line 107)
Error in A (line 7)
garlic(Sys,Exp);

Please help.

Regards,
Abbey

Posted: **Thu Jan 28, 2016 7:58 am**

Well you have a couple problems with your inputs, fixing them up and you get:

Code: Select all

clear

SysA.S = 1/2;
SysA.g = 2.012;
SysA.Nucs = '1H,1H';
SysA.A = mt2mhz([16.9,10.9]/10);
SysA.lwpp = 0.55;
% or
% SysA = struct('S',1/2,'Nucs','1H,1H','g',2.012,'A',mt2mhz([16.9,10.9]/10),'lwpp',0.55);

SysB.S = 1/2;
SysB.g = 2.023;
SysB.Nucs = '1H';
SysB.n = 1;
SysB.A = mt2mhz(9/10);
SysB.lwpp = 0.55;
% SysB = struct('S',1/2,'Nucs','1H','g',2.023,'A',mt2mhz(9/10),'lwpp',0.55);

Exp.mwFreq = 9.137;
Exp.Range = [310 340];
Exp.nPoints = 64293;
% or
% Exp = struct('Range',[310, 340],'mwFreq',9.137,'nPoints',64293);

garlic({SysA SysB},Exp);

Now you'll probably notice I left out sys.tcorr, that is only important if you also provide anisotropy in g or A.

Are you trying to simulate a spin correlated radical pair? If you are, easyspin doesn't straightforwardly handle it, and garlic definitely doesn't do it. There are a few ways to simulate a SCRP with ES, though they involve using pepper, identifying the polarization of the transitions, and adding those transition together for the total spectrum. See http://easyspin.org/easyspin/documentat ... ation.html

Posted: **Thu Jan 28, 2016 8:42 am**

Thank you Dr. Matt for the prompt reply, it really helped me resolve the simulation error.

I'm new to EPR and am trying to simulate the radical pair formed on photoexcitation of donor-acceptor (D-A) system. However I'm not sure of a spin correlated radical pair in my D-A system as we aren't seeing any triplet present in the system from nanosecond data (is it necessary to see the triplet for SCRP mechanism?). Sir, how good is garlic while simulating the radical pair at 77K as compared to the chili?

Your reply was quite helpful and thanks once again for the prompt and fruitful solution to the simulation error.

Regards,
Abbey

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