THEORETICAL INVESTIGATIONS OF THE ELECTRONIC-PROPERTIES OF VANADIUM-OXIDES .1. PSEUDOPOTENTIAL PERIODIC HARTREE-FOCK STUDY OF V2O5 CRYSTAL-LATTICE

A series of pseudopotential periodic Hartree-Fock calculations has been performed on a V2O5 crystal. The optimized V-O bond lengths and stretching force constants are found to be in good agreement with experiment. The band structure and density of states are reported, and in contrast with tight-binding calculations there is no gap in the valence band. From the projected density of state it is shown that the V atom d orbitals play an important role in the bonding and therefore that this oxide is partially ionic. Three types of V-O bonds are recognized in this structure: the mainly covalent vanadyl bond, the ionic bond connecting the central vanadium to the chain oxygen, and the electrostatic-van der Waals bond which ensures the stacking of the layers.