How to calculate oscillator strength within DFT?

[sdeepmanav]

Dear VASP users,

Does VASP output allows for an approximation of the oscillator strength by the formula shown in the following?

fij = 4πmeωij |Dij|2/3he2

where ωij is equal to the angular frequency of light needed to promote an electron from state i to state j and Dij represents the transition dipole formed upon this excitation.

Can someone suggest me how I can do it?

Thanks and regards
Sandeep

[ferenc_karsai]

So that's basically dielectric properties what you need.

Please read this chapter in the VASP wiki:
wiki/index.php/Category:Dielectric_Properties

Also the following paper describes what is done in VASP:
https://journals.aps.org/prb/abstract/1 ... .73.045112

[sdeepmanav]

Dear Ferenc,

Thank you for your response. Actually my main concern is about Dij parameters which is a transition between an initial state i and a final state j. I wonder how to calculate this terms ?. Is it possible to write this term directly in OUTCAR? Is the squares of transition dipole moment considered only between the highest valence band and the lowest conduction band only or for all bands?

Thanks and regards

Sandeep

[ferenc_karsai]

Please read that thread:
forum/viewtopic.php?f=4&t=17890

It should answer your question.