three-dimensional magnetization

[radovanh]

Hello.

I would like to calculate magnetization with CURRY for various orientations of the magnetic field.
From the documentation, I guess I need to use Exp.SampleFrame command.

So I generated simple loop for three different Euler angles

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Temp=2;  %K
Field=500; %mT

npoints=10; %number of point for PI section
delta=pi/(npoints);
count=0;
%alfa
for i = 0:2*npoints
    alfa=i*delta;
%beta
for j = 0:npoints
    beta=j*delta;
%gama
for k = 0:2*npoints
    gama=k*delta;
    count=count+1;
    mag=simulate(x0,alfa,beta,gama,Temp,Field);
    f_alfa(count)=alfa;
    f_beta(count)=beta;
    f_gama(count)=gama;
    Magnetization(count)=mag;
    

end
end
end

where the function "simulate" calculates the magnetization for given angles:

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Exp.MolFrame = [0 0 0];  

Exp.CrystalSymmetry = 'P1';  % crystal space group
Exp.SampleFrame = [gama beta alfa]; 
simspc = curry(FitSys,Exp,Opt);

However, I do not know how to properly transfer Euler angles to information about X,Y,Z coordinates. So I do not know for which orientation of the magnetic field the curry calculates magnetization. So in other words I would like to calculate (Bx,By,Bz).

Any help is truly welcomed

Radovan

[Stefan Stoll]

Have a look here: https://easyspin.org/easyspin/documenta ... es.html#CL

This describes how to get axes from the Exp.SampleFrame Euler angles.

[ecizmar]

Dear colleagues,
I have an impression that the Documentation regarding the use of Exp.MolFrame and Exp.SampleFrame for curry is not entirely correct. In the user guide for curry https://easyspin.org/easyspin/documenta ... curry.html, it is stated:
"curry can also calculate the magnetic moment and molar magnetic susceptibility of single crystals. For this, provide three things: (a) the orientation of the crystal in the spectrometer in Exp.SampleFrame, (b) the space group of the crystal in Exp.CrystalSymmetry, and (c) the orientation of the molecular frame relative to the crystal frame in Exp.MolFrame. You can omit the latter two, in which case the space group is assumed to be P1, and the molecular frame is assumed to be aligned with the crystal frame. You can't omit Exp.SampleFrame."

If Exp.MolFrame and Exp.CrystalSymmetry are omitted; it will always calculate the powder magnetic moment (or pepper will calculate powder EPR spectra), regardless of setting in Exp.SampleFrame. The correct way is described in https://easyspin.org/easyspin/documenta ... alsim.html for the crystal simulation of EPR using pepper.

The example cobaltdimer_magnetization.m shows the correct way for curry also - first you set

Code: Select all

Exp.MolFrame = [0 0 0]

and then define the direction of the magnetic field using Exp.SampleFrame.
Concerning this example, also the correct way to set x,y,z direction of the field is:

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% Calculate crystal data for three crystal orientations
Exp.SampleFrame = [0 0 0];  % crystal z axis along field
Exp.SampleFrame = [0 -pi/2 0];  % crystal x axis along field
Exp.SampleFrame = [0 -pi/2 -pi/2];  % crystal y axis along field

[Stefan Stoll]

Thanks, you are correct - thanks for reporting! We'll correct the documentation for curry.