Optical properties of BiSBr and BiSeBr crystals Original Research Article

Optical properties of BiSBr and BiSeBr crystals were investigated by the full potential linearized augmented plane wave (FP-LAPW) method with density-functional theory (DFT). The complex dielectric function and optical constants, such as optical absorption coefficient, refractive index, extinction coefficient, energy-loss spectrum and reflectivity, were calculated and compared in the energy range of 0–30 eV. Origin of anisotropic behavior of optical spectra was also discussed. The plasmon energy ℏωp was estimated to be 18 eV for BiSeBr and 20 eV for BiSBr crystal.