Spectra of fundamental optical functions of BeSe

Abstract

Spectra of sets of fundamental optical functions of BeSe were derived for the range of 0–25 eV. Calculations were performed using an experimental ɛ2(E) spectrum and integral Kramers-Kronig relations. Using combined Agrand diagrams, the spectra of permittivity and characteristic energy losses of electrons were decomposed into elementary transverse and longitudinal components. The main parameters of these components were determined. The results obtained were compared with theoretical spectra of optical functions calculated using the OPW and APW methods and with the energy bands obtained in an ab initio GW approximation.