Valence-band excitations in V2O5

We present a joint theoretical and experimental investigation of the electr onic and optical properties of vanadium pentoxide. Electron energy-loss spe ctroscopy in transmission was employed to measure the momentum-dependent lo ss function. This in turn was used to derive the optical conductivity, whic h is compared to the results of band-structure calculations. A good qualita tive and quantitative agreement between the theoretical and the experimenta l optical conductivity was observed. The experimentally observed anisotropy of the optical properties of V2O5 could be understood in the light of an a nalysis of the theoretical data involving the decomposition of the calculat ed optical conductivity into contributions from transitions into selected e nergy regions of the conduction band. In addition, based upon a tight bindi ng fit to the band structure, values are given for the effective V 3d(xy)-O 2p hopping terms and are compared to the corresponding values for alpha'-N aV2O5.