Energy bandstructure and Fermi surface of LaB6by a self-consistent APW method

Abstract

Self-consistent calculations of the energy bandstructure of LaB₆, which has attracted interest as an electron beam source, are carried out using the usual nonrelativistic, symmetrized APW method. A one-electron potential is constructed on the basis of the X alpha method. The calculation is repeated for two special values of the exchange parameter, i.e. alpha =1.0 and 2/3. The two calculated bandstructures do not differ significantly in their essential features. They are characterized by wide B sp bands and La sd bands. The La d bands appear near the Fermi energy, E_F, and a strong hybridization of the La d and B sp bands occurs. The strong hybridization causes a large wavevector dependence of the d bands, and E_F cuts one such d band. These results account well for various small effective masses observed in LaB₆. The calculated density of states for the valence bands agrees well with a recent X-ray photoemission measurement.