Ab initio SCF and limited CL calculations on the d-d transitions in NiO

Abstract

SCF and limited Cl calculations on d-d transitions in NiO are presented. The calculations were performed on NiO610-, stabilized by an electrostatic field. Closed Ni d-orbitals turned out delocalized from the calculations, but this was found to be an artifact of the calculation. The Cl calculation showed that the d-electrons are in fact well localized on the metal, and that this localization may be obtained after pairwise rotations between the appropriate delocalized orbitals. The configuration interaction results are thus insensitive to the choice of reference state, provided that excitations describing the pairwise rotation are included in the Cl expansion; only minor effects were obtained when excited-state orbitals instead of ground state orbitals were used in the calculations. A crystal-field treatment, based on SCF wave functions, yielded excitation energies in good agreement with the Cl results. The computed results are satisfactory and the order3Aig2g3Tig2g3Tig1g and1Eg is proposed for the ground and first three excited states. © 1977 Taylor & Francis Group, LLC.