Electronic structure of V2O5:: 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 O 2p and crystal field split V 3d states. Strong deviations of the VO6 octahedra from cubic coordination give rise to the narrow split-off conduction band as a characteristic feature of V2O5. Furthermore, we demonstrate that distortions of the octahedra along the crystallographic c axis drastically increase the bonding-antibonding splitting of the V 3d(xz)/3d(yz) derived bands, aawhereas distortions perpendicular to the c axis reduce the bandwidth of the split-off V 3d(xy) bands. Both effects contribute to the stability of V2O5 and enhance the optical band gap.