Dear VASP team,
I am trying to compute optical spectra with GW-BSE. I have followed the tutorial for LiF and I get the same dielectric function shown on the tutorial webpage. I have used that dielectric function to compute the absorption coefficient \alpha and transmission T according to the Beer-Lambert law:
T = exp (-\alpha * d) where d is the thickness of the sample
My transmission spectrum says that a 2mm sample of LiF is opaque to visible light, which is not true. I can get the correct transmission spectrum but only by using a very small d value. Can you suggest anything that might fix this problem?
Best wishes,
Harry