Covalent bonding and bandgap formation in intermetallic compounds: a case study for Al₃V

We demonstrate that a special hybridization between the Al(s, p) and V(d) orbitals which is responsible for forming of a deep pseudogap near the Fermi level in the Al₃V compound is also associated with the formation of covalent bonds. We analyse the charge distribution in the elementary cell and find an enhanced charge density along the Al-V bonds and certain Al-Al bonds which is characteristic for covalent bonding. The role of the point-group symmetry and the character of the hybrid orbitals forming the covalent bonds are investigated. It is demonstrated that the deep pseudogap close to the Fermi level arises from the bonding-antibonding of the hybrid orbitals.