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Dipole transition matrix elements from LOPTICS
Posted: Wed Jun 04, 2014 9:23 pm
by ssharifz
I would like to compute the dipole transition matrix elements between valence and conduction states. I believe that with LOPTICS, these matrix elements will be calculated but I don't know how to access them. They are not written out in the OUTCAR with LOPTICS on. Can anyone tell me how to get these matrix elements?
Thank you in advance.
Dipole transition matrix elements from LOPTICS
Posted: Thu Jun 05, 2014 12:01 am
by ccao
If I understand correctly, you will have to set NPAR=1 and KPAR=1 with LOPTICS on. VASP will then output a binary file called "OPTICS". However, I don't know the detailed format & the unit used in that file.
Re: Dipole transition matrix elements from LOPTICS
Posted: Tue Apr 28, 2015 7:03 am
by 5-1669
I had been looking for this and I think I found the answer in the code (v 5.3.5), so posting it here to verify and for others reference if correct.
The elements are written in binary format to the WAVEDER file (and can be written in text format by uncommenting a line in linear_optics.F that calls a function to write the formatted WAVEDERF file)
The elements of the derivatives with respect to k_i, i=x,y,z, <phi_nk|d/dk_i|phi_nk> are equal to - i <phi_nk|r_i|phi_nk>.