Crystal Simulations

[sterulo]

Hi,

I want to simulate the EPR spectrum of NV centres in diamond. How can I simulate the absorption lines of all four NV axes in one plot? Do you have any hints for me?

Thank you!

[ShutianLu]

I used the function pepper to simulate the diamond NV center. In addition to the regular spin system and experimental parameters (g,A, mwFreq, etc), the function takes:

1. The diamond crystallographic group (Exp.CrystalSymmetry)
2. The local symmetry of the NV center (Exp.MolFrame)
3. The relative crystal orientation in regards to the spectrometer (Exp.CrystalOrientation), which can be used for specifying the axis to which the NV center is aligned

These parameters can be specified as:

Code: Select all

% Diamond crystallographic group (Fd3m or 277);
Exp.CrystalSymmetry = 227;
% NV center local geometry (C3v local symmetry)
Exp.MolFrame = [pi/4 acos(1/sqrt(3)) 0];
% Specific axes 
% <100> axis
Exp.CrystalOrientation = [0 0 0];
% <110> axis
Exp.CrystalOrientation = [0 pi/4 0];
% <101> axis
Exp.CrystalOrientation = [0 0 pi/4];
% <111> axis
Exp.CrystalOrientation = [pi/4 mag 0];

The three numbers in Exp.MolFrame and Exp.CrystalOrientation give a set of Euler angles to describe the relative orientation of the NV center to in diamond lattice and the relative orientation of the diamond to spectrometer, respectively. If the Euler angles for a certain axis is used for Exp.CrystalOrientation, the simulation will generate a spectrum for the specified axis.

As for absorption lineshape, I usually simulate everything in derivative lineshape then use cumsum function to calculate the integral.

[Matt Krzyaniak]

You can simulate absorptive or emissive lineshapes in pepper by passing the experimental parameter Exp.Harmonic = 0, the default in pepper is the first harmonic which is the derivative.

[sterulo]

I used the function pepper to simulate the diamond NV center. In addition to the regular spin system and experimental parameters (g,A, mwFreq, etc), the function takes:

1. The diamond crystallographic group (Exp.CrystalSymmetry)
2. The local symmetry of the NV center (Exp.MolFrame)
3. The relative crystal orientation in regards to the spectrometer (Exp.CrystalOrientation), which can be used for specifying the axis to which the NV center is aligned

These parameters can be specified as:

Code: Select all

% Diamond crystallographic group (Fd3m or 277);
Exp.CrystalSymmetry = 227;
% NV center local geometry (C3v local symmetry)
Exp.MolFrame = [pi/4 acos(1/sqrt(3)) 0];
% Specific axes 
% <100> axis
Exp.CrystalOrientation = [0 0 0];
% <110> axis
Exp.CrystalOrientation = [0 pi/4 0];
% <101> axis
Exp.CrystalOrientation = [0 0 pi/4];
% <111> axis
Exp.CrystalOrientation = [pi/4 mag 0];

The three numbers in Exp.MolFrame and Exp.CrystalOrientation give a set of Euler angles to describe the relative orientation of the NV center to in diamond lattice and the relative orientation of the diamond to spectrometer, respectively. If the Euler angles for a certain axis is used for Exp.CrystalOrientation, the simulation will generate a spectrum for the specified axis.

As for absorption lineshape, I usually simulate everything in derivative lineshape then use cumsum function to calculate the integral.

Thanks for your reply.
Though I was already at that point but I haven't managed to get all absoprtion lines for each NV orientation in code or do I have to simulate each line in a separate code by just changing the Exp.MolFrame for each orientation?