Geometric and electronic structure of vanadium pentoxide: A density functional bulk and surface study

Density-functional theory (DFT) studies are performed to examine geometric and electronic properties of orthorhombic bulk V₂O₅ as well as of its (010) oriented surface. Electronic states, total energies, as well as atom forces (used to obtain equilibrium geometries) are computed with the ab initio full-potential linear augmented plane wave method. The V₂O₅ (010) surface is modeled by periodic single layers in a repeated slab geometry, which is justified by the weak electronic interlayer coupling found in the bulk calculations. The electronic structure of the V₂O₅ (010) single-layer slabs, represented by their valence densities of states (DOS) and its atom contributions, is compared with results of bulk V₂O₅ and with previous results obtained by DFT surface cluster studies. The comparison yields good qualitative agreement between the different approaches, which confirms the local nature of interatomic binding in V₂O₅. Further, the computed valence DOS is used to interpret recent experimental results from photoemission on V₂O₅ (010), which suggests that differently coordinated oxygen sites at the surface can be identified in the spectrum. Thus, V₂O₅ (010) photoemission spectra may be used to monitor the participation of oxygen ions in respective surface reactions.