Surface electronic structure of Ce in the α and γ phase

Abstract

The surface electronic structure of Ce in the \ensuremath{\alpha} and \ensuremath{\gamma} phase has been calculated using a film linearized-muffin-tin-orbitals method. The bonding in Ce is found to be mainly metallic in character. The width of the 4f band in \ensuremath{\alpha}-Ce is found to be about 0.7 eV both in the bulk and at the surface; in \ensuremath{\gamma}-Ce it is slightly narrower, about 0.6 eV. The calculated work function of \ensuremath{\alpha}-Ce is in good agreement with experimental data. Cross sections for the bremsstrahlung isocromat (BIS) processes have been calculated in a fully relativistic framework, and good agreement with experiment is obtained for the itinerant peak in the BIS data near ${\mathit{E}}_{\mathit{F}}$. We find our results consistent with an itinerant f-electron picture for \ensuremath{\alpha}-Ce, and thereby consistent with a picture for the \ensuremath{\gamma}\ensuremath{\rightarrow}\ensuremath{\alpha} transition that is from localized (and magnetic) to itinerant (bonding and nonmagnetic) f-electron behavior, i.e., a Mott transition, as opposed to a Kondo volume collapse picture involving a transition between localized states of the f electrons. We also predict that the surface of \ensuremath{\alpha}-cerium is \ensuremath{\gamma}-like.