Properties of LaB6 elucidated by density functional theory -: art. no. 193403

Although lanthanum hexaboride has been routinely used as a cathode material in commercial devices for over 20 years, a microscopic explanation for its amazing electron-emission properties is still lacking. We present results of ab initio calculations, which reproduce the observed low work function, identify an as yet unreported surface state partly responsible for the emission, and yield consistent values for the heat of evaporation of La and B atoms from the surface, as well as for the migration enthalpy of La in the bulk. Our computed surface phonon spectral density compares well with that measured by high-resolution inelastic electron scattering. Bulk phonon dispersion relations, obtained in the frozen phonon approximation, show the rapid flattening of the acoustic branches observed in this class of materials by inelastic neutron scattering.