Electronic structure ofV2O5:  Role of octahedral deformations

We present results of all-electron electronic-structure calculations for semiconducting vanadium pentoxide. The calculations are based on density-functional theory within the local-density approximation and employ the augmented spherical wave method in its scalar-relativistic implementation. The electronic properties are modified significantly by strong hybridization between $\mathrm{O}2p$ and crystal field split $\mathrm{V}3d$ states. Strong deviations of the ${\mathrm{VO}}_{6}$ octahedra from cubic coordination give rise to the narrow split-off conduction band as a characteristic feature of ${\mathrm{V}}_{2}{\mathrm{O}}_{5}.$ Furthermore, we demonstrate that distortions of the octahedra along the crystallographic $c$ axis drastically increase the bonding-antibonding splitting of the $\mathrm{V}{3d}_{\mathrm{xz}}{/3d}_{\mathrm{yz}}$ derived bands, whereas distortions perpendicular to the $c$ axis reduce the bandwidth of the split-off $\mathrm{V}{3d}_{\mathrm{xy}}$ bands. Both effects contribute to the stability of ${\mathrm{V}}_{2}{\mathrm{O}}_{5}$ and enhance the optical band gap.