EasySpin forum

Hi all,
A question for the experts here. When I run the following script I was expecting the final trace in the plot attached below to be a flat line.
This should be the difference between two spin species with hyperfine added together and the same two species calculated in one go with a value sys.dip = 0. When I do not use any hyperfine this is essentially what does happen, also attached image below.
Any suggestions where my stupid mistake lies?

thanks
F

My script:
clear, clc, clf;

Exp.mwFreq = 9.5;
Exp.Range = [260 360];
Exp.Harmonic = 1;
Exp.nPoints = 1024;

%individual spins and their parameters
% Species 1
SL.S =1/2;
SL.g = [2.008 2.006 2.0023];
SL.lwpp = 1.5;
SL.Nucs = '14N';
A_SL = [7 7 35]2.804;
SL.A = A_SL;
% Species 2
Cu.S = 1/2;
Cu.g = [2.05 2.05 2.264];
Cu.lwpp = 1.5;
Cu.Nucs = 'Cu,14N';
A_Cu1 = [5 5 186]2.804;
A_Cu2 = [13 13 15]*2.804;
Cu.A = [A_Cu1; A_Cu2];

% calculate the EPR spectra
[~,SLspc] = pepper(SL, Exp);
[~,Cuspc] = pepper(Cu, Exp);
Sum = (SLspc + Cuspc);
Sum = Sum/max(Sum);

% Coupled system with and without a value for Sys.dip
Sys.S = [1/2 1/2];
Sys.g = [2.05 2.05 2.264; 2.008, 2.006, 2.0023];
Sys.gFrame = [0 0 0 ; 0 0 0]pi/180;
Sys.Nucs = 'Cu,14N,14N';
Sys.A = [5, 5, 186, 0, 0, 0; 13, 13, 15, 0, 0, 0; 0, 0, 0, 7, 7, 35]2.804;
Sys.lwpp = 1.5;
Sys.dip = 30;
Sys.J = 0;
Sys.eeFrame = [0 0 0]*pi/180;

Opt.Method = 'matrix';
[~, spc_sim_D] = pepper(Sys, Exp, Opt);
spc_sim_D = spc_sim_D/max(spc_sim_D);

Sys1.S = Sys.S;
Sys1.g = Sys.g;
Sys1.lwpp = Sys.lwpp;
Sys1.gFrame = Sys.gFrame;
Sys1.Nucs = Sys.Nucs;
Sys1.A = Sys.A;
Sys1.dip = 0;
Sys1;J = 0;
Sys1.eeFrame = [0 0 0]*pi/180;

Opt.Method = 'matrix';
[B, spc_sim_noD] = pepper(Sys1, Exp, Opt);
spc_sim_noD = spc_sim_noD/max(spc_sim_noD);

% Create plots of the various comparisions
diff = (spc_sim_D - Sum)-1; % take difference of two species and coupled species
diff2 = (spc_sim_D - spc_sim_noD)-2; % take difference of two coupled species with/without coupling
diff3 = (spc_sim_noD - Sum)-3; % take difference of two species and non-coupled species

plot (B,Sum,'r', B,spc_sim_D,'b',B,spc_sim_noD,'g',B,diff,'b',B,diff2,'g',B, diff3, 'r')

Look here for the typo
Sys1;J = 0;

sorry, that was simply a typo in my pasted script. the examples shown are run with Sys1.J=0 so there is still clearly an issue here. the issue gets much smaller when you increase the microwave frequency to 95 GHz, so it seems related to the HFC and the Sys.dip!