EasySpin forum

Dear all,
For the first time to use EasySpin simulation, I have some questions I would like to ask you.
I tried to simulate the rotation pattern of a single crystal of pentacene, and now the laboratory coordinate system is known as x.y.z, Where z is the direction of the magnetic field,and the angle between the ab plane of the crystal and the x-axis is known. Most notably, we know that the yz plane of the crystal molecule and the magnetic field are at the same horizontal plane.I'm trying to find the angles between the axes in different coordinates, and then I'm trying to figure out the Euler angles, but the simulated image still did not agree with the peak position and direction obtained by the experiment. I would like to ask how I should specify Exp.molframe and cori0 now or is there any better solution to draw their rotation pettern?
Below is my coordinate system diagram and some problematic code, hope to get some pointers.

Exp.Temperature = [0.08 0.16 0.76];
Exp.MolFrame = [-32.2877 104.5734 -0.4336]*pi/180;    % molecular frame tilted within crystal
cori0 = [180.1687 74.3489 165.6990]*pi/180;             % initial crystal orientation in lab frame
Exp.CrystalOrientation = cori0;

nRot_L = [1;0;0];                         % rotation axis = x axis of lab frame
rho =0*pi/180;                          % rotation angle
cori = rotatecrystal(cori0,nRot_L,rho);   % rotate crystal by rho around nRot
Exp.CrystalOrientation = cori;   % setting a series of crystal orientations
pepper(Sys,Exp);

It looks like you are using version 5.2.x. I recommend switching to 6.0.0-dev.*, which has a improved support for crystal rotations, using the new field Exp.SampleRotation.

Here is an example for the P1 center in diamond, which you might use as a starting point for your case:

clear, clf

% Substitutional nitrogen center (P1) in diamond
P1.g = 2.0024;
P1.Nucs = '14N';
P1.A = [81 114];             % MHz
P1.lwpp = 0.03;              % mT

% Experimental parameters
Exp.mwFreq = 9.5;            % GHz
Exp.CenterSweep = [339 10];  % mT

% P1 and crystal orientation, crystal symmetry
ma = 54.736;                                % magic angle (deg)
Exp.MolFrame = [45 ma 0]*pi/180;            % mol. frame ori. of P1 in crystal
Exp.CrystalOrientation = [0 ma 0]*pi/180;   % crystal ori. in spectrometer
Exp.CrystalSymmetry = 'Fd-3m';              % space group of diamond (#227)

% Sample rotation axis and angle
nRot = 'x';                  % = x-axis of lab frame (xL)
rho = deg2rad(0:10:180);     % rotate in steps over 180 degrees (half turn)

for k = 1:numel(rho)
  Exp.SampleRotation = {rho(k),nRot};
  [B,spc(k,:)] = pepper(P1,Exp);
end

stackplot(B,spc,3);
xlabel('magnetic field (mT)');

Thanks for your reply,I still have a small question, how should the population ratio be set in 6.0.0-dev.*? Using the same setting method as version 5.2.35 will hint Exp.Temperature must be a single number.

Exp.Temperature = [0.01 0.13 0.56];%version 5.2.35

Use the field Sys.initState to specify non-thermal spin polarization. See the user guide on spin-polarized systems about this To access the EasySpin documentation in the latest 6.0.0-dev version, type easyspin docin the MATLAB command window.

It looks like you are simulating a spin-1/2 P1 center rather than an spin-1 NV center, so the spin polarization vector must contain 2 elements rather than 3.

Thank you very much for your valuable advices.
I want to study the rotational spectrogram of the single-crystal triplet, the crystalroadmap case given in version 6.0, and I want to know how to determine the code for generating directions in a single plane, for example, would you like to generate a plane direction perpendicular to the x-axis of the laboratory coordinate system (which is also approximately the x-axis of the molecule) , in this case rotN = [110] ? Hope to receive your reply, thank you very much!

To rotate around the x axis of the laboratory, use Exp.SampeRotation = {phi,'x'} or Exp.SampleRotation = {phi,[1;0;0}}. (This works in EasySpin 6, but not 5.2.)

Dear teachers, I would like to ask a question. On the use of the latest version of easyspin in the two case simulation, enter the same parameters, the two are very different, want to ask the two code major differences in what? I may be some aspects of the input is not quite right, please give me more advice teachers! The case I'm referring to is crystalrotation. m and crystalroadmap.m.

% Generate orientations in a single rotation plane
rotN = [1 1 0]; % rotation axis
Hello teacher, the meaning of this code is to refer to the crystal XY plane, Z axis for the rotation axis?

Is this from the resfields_roadmap.m example? There, rotN is the rotation axis, expressed in the lab frame.