Metal-insulator transition in transition metal oxides

Electronic band structure calculations for TiO, VO, MnO, FeO, CoO, and NiO suggest that the 4s band becomes degenerate with the 3d band at VO and thus helps to destroy the Mott insulator state. The large difference in lattice constant between the metallic and insulating oxides is well accounted for in terms of the Mott transition. Calculated values of the crystal field splitting 10 Dq are about 70% of experimental ones.