Surface electronic structure of γ-uranium

It is interesting to study the surface electronic structure of uranium in the context of f-electron localization as the 5f shell is filled. Accordingly, we have used the film-linearized-muffin-tin-orbital method to calculate the surface electronic structure of γ-uranium with body-centered-cubic structure. This all-electron self-consistent fully relativistic calculation has been done for a five-layer slab with (100) surface using two lattice constants (differing by about 1%) corresponding to different experimental information. Our calculated work functions of 3.60 and 3.82 eV for the two lattice constants both provide excellent agreement with the experimental results, which range from 3.63 to 3.90 eV. The calculated density of states and the charge distribution show stronger hybridization of 5f with 6d electrons than that of δ-plutonium. Our calculations indicate that the surface enhancement of 5f localization (i.e., relative to the bulk behavior) is much stronger for uranium than for plutonium. This increase of localization at the surface may have important consequences for surface reconstruction, chemisorption, and other surface behavior