How to obtain refractive index, extinction coefficient, and electron energy-loss function

[alok_shukla1]

Dear Experts,
I am working on the optical properties of a 2D heterostructure. Based on earlier posts, I calculated the real and imaginary parts of the dielectric constant.
I am also willing to calculate the refractive index, extinction coefficient, and electron energy-loss function.
Any guidance on how to proceed would be very helpful.

[alexey.tal]

Dear alok_shukla1,

Thank you for your question.
You can find a detailed guide on how to calculate EELS in VASP on our wiki.
We don't explicitly write out the extinction coefficient and the refractive index but they can be easily found from the dielectric function using the relation:

$$
\sqrt{\varepsilon}=n+ik,
$$
where \(\varepsilon\) is the dielectric function and \(n\) and \(k\) are the refractive index and the extinction coefficient, respectively.

Best wishes,
Alexey