Geometric and electronic structure ofγ−V2O5:Comparison betweenα−V2O5andγ−V2O5

Electronic structure calculations of $\ensuremath{\gamma}\ensuremath{-}{\mathrm{V}}_{2}{\mathrm{O}}_{5}$ are presented and compared to the electronic structure of the more commonly known $\ensuremath{\alpha}\ensuremath{-}{\mathrm{V}}_{2}{\mathrm{O}}_{5}.$ The different ${\mathrm{VO}}_{5}$ building blocks in $\ensuremath{\gamma}\ensuremath{-}{\mathrm{V}}_{2}{\mathrm{O}}_{5}$ are investigated in terms of the angular momentum projected density of states. Since the same structural unit is also found in the $\ensuremath{\alpha}\ensuremath{-}{\mathrm{V}}_{2}{\mathrm{O}}_{5}$ phase, it is possible to compare the electronic structure with respect to differences in the geometry of the ${\mathrm{VO}}_{5}$ pyramids. Electron energy-loss spectroscopy is applied as a sensitive probe of the electronic structure and reveals differences in the fine structure of the oxygen K ionization edge which are confirmed by the simulation.