QuantumATK Forum
QuantumATK => General Questions and Answers => Topic started by: ams_nanolab on June 23, 2015, 10:02
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In the script
http://quantumwise.com/documents/tutorials/latest/SiliconOptical/index.html/chap.Si.Band.html
It is given....
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# get the real and imaginary part of the e_xx component of the dielectric tensor
d_r = spectrum.evaluateDielectricConstant()[0,0,:]
d_i = spectrum.evaluateImaginaryDielectricConstant()[0,0,:]
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what do I do to select the e_zz component of the tensor? I cant understand the index in [0,0,:] as it is unlike [x,y,z]
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If you want to select e_zz use
d_r = spectrum.evaluateDielectricConstant()[2,2,:]
evaluateDielectricConstant and same for iImaginary will indeed give you the dielectric tensor for each energy point.
You can print the tensor for the point zero, for example with:
spectrum.evaluateDielectricConstant()[:,:,0]
with he first two indices you select the component you wish, e.g e_xx, e_zz, e_xy, ...
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Thanks :D
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Another thing... It is sometimes important (for nanostructures) to evaluate the optical spectra not just in individual directions like xx, yy and zz but take a sum or trace of the dielectric tensor like e=e_xx+e_yy+e_zz and do the calculations for optical absorption.
How to modify the script for that ???
would
d_r = spectrum.evaluateDielectricConstant()[0,0,:]+spectrum.evaluateDielectricConstant()[1,1,:]+spectrum.evaluateDielectricConstant()[2,2,:]
do the trick? or something else is needed ???
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Please reply... this is a bit urgent.. :(
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The trick is correct. You can are summing the diagonal components.
You may also want to consider taking the average in a similar way for the calculation of optical absorption.
But this is up to you.
The dielectric tensor for a nanostructure has the same meaning as the one for a bulk system.
You are free to do whatever you wish with it :)