SURFACE ELECTRONIC-STRUCTURE OF CE IN THE ALPHA AND GAMMA-PHASE

The surface electronic structure of Ce in the alpha and 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 alpha-Ce is found to be about 0.7 eV both in the bulk and at the surface; in gamma-Ce it is slightly narrower, about 0.6 eV. The calculated work function of alpha-Ce is in good agreement with experimental data. Cross sections for the bremsstrahlung isochromat (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 E(F). We find our results consistent with an itinerant f-electron picture for alpha-Ce, and thereby consistent with a picture for the gamma --> 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 alpha-cerium is gamma-like.