THE ENERGY DIAGRAM OF NIO WITHIN AN LCAO-LSDA+U APPROACH

The itinerant LCAO picture based on localized atomic-like orbitals has been used to study the electronic ground state of NiO. The U-correcte d local spin-density approximation (LSDA+U) yields energy-dispersion c urves which show satisfactory agreement with the angular photoemission measurements. As a result the d states appear as narrow and well iden tified bands located above the 2p oxygen bands. The on-site Coulomb en ergy U increases the 2p character within the upper d valence band but not to the extent that NiO can be considered as a charge-transfer insu lator.