Electronic defect structure in TiO and MnO

The electronic structure, charge distribution, magnetic moment, and binding energies are studied in transition-metal monoxides using the discrete variational method in the embedded scheme within the local density formalism. Defect structures such as 1:0, 2:1, 4:1, and 7:2 (vacancy:interstitial ratio) were evaluated with respect to the ideal structure. Ti loses its moment in the 4:1 structure as the 3d electrons are depopulated in the process of redistribution. Mn shows the highest magnetic moment as in the atomic case but varies over a range of 2.23-4.96 μ_B depending upon the defect structure. Our calculations predict greater stability for the 2:1 defect structure in TiO and MnO. The interstitial metal ion tends to be in a trivalent state in accord with experiments.