Electronic structure, optical properties and Compton profiles of Bi2S3 and Bi2Se3

In this paper, we present the Compton profiles of Bi2S3 and Bi2Se3 using our 20 Ci Cs-137 Compton spectrometer. To compare our experimental data, we have computed the Compton profiles, energy bands and density of states using linear combination of atomic orbitals with density functional theory (DFf) and Hartree-Fock (HF) scheme. It is seen that hybrid functional involving HF and DFT approximations gives a relatively better agreement with experimental momentum densities than other approximations of DFT. We have also reported the band structure, density of states, valence charge densities, dielectric functions and electron energy loss spectra using full potential linearized augmented plane wave scheme. On the basis of charge densities, Mulliken's population data and equal-valence-electron-density profiles, Bi2S3 is found to be more ionic than Bi2Se3. The calculated dielectric functions for the parallel and perpendicular polarizations show a small anisotropic effect. The electron energy loss spectrum for Bi2Se3 is found to be in good agreement with the available experimental data. (C) 2011 Elsevier Masson SAS. All rights reserved.