On the electronic structure of surface Pt–Sn alloys

Abstract

The electronic structures of Pt 3Sn(111),Pt 3Sn/Pt(111) and Pt 2Sn/Pt(111) surfaces are studied using the linear-muffin-tin-orbital tight-binding method in the atomic-sphere approximation. Both ideal and rumpled surface terminations are considered. The hybridization between Pt d- and Sn p-electrons, respectively, leads to a lowering of the local density of electronic states at the Fermi level and to a downward shift of the Pt local d-band, which accounts for the lower reactivity of the Pt–Sn surfaces. The effect is more pronounced for rumpled surfaces. Generally, the situation is similar to that of bimetallic transition-metal surfaces. The initial-state approximation is used to predict Pt(4f) core-level shifts. We find moderate shifts of either sign, but the d-band centre of gravity moves to higher binding energies, as compared to Pt(111), in most cases. The correlation between the surface reactivity and core-level shifts, respectively, seems to be less favourable than at bimetallic transition-metal surfaces