First-principles Hartree-Fock description of the electronic structure and magnetism of hole and electron states in MnO

First-principles periodic Hartree-Fock calculations of the first ionized (hole) state of MnO in both the ferromagnetic and antiferromagnetic AF(II) spin configurations are reported. Mulliken populations, charge and spin distributions and atom-projected densities of valence band states provide direct evidence of O(p) holes in agreement with recent experimental and theoretical studies of NiO. Calculations find the energy of the self-trapped hole to be lower than that of the delocalized hole which suggests small-polaron behaviour, in agreement with recent observations. Three different spin arrangements of the hole with respect to the lattice are reported from which the magnetic contributions to the energy are obtained in addition to the lattice relaxation energy associated with an increase in the Mn2+-O- separation. The relaxation energy is close to the reported activation energy for hole conductivity, which further supports small-polaron behaviour of holes in MnO. An excited configuration of the hole state has been determined from broken-symmetry calculations which Mulliken population and direct charge and spin distribution analyses suggest is similar to d(4). Also reported are similar calculations of the first electron addition state of MnO which indicate that this is essentially a d(6) state. Unlike that of the hole state, the energy of the self-trapped electron is found to be higher than that of the delocalized carrier which suggests intermediate- or large-polaron behaviour of the free carrier. However, a localized state is predicted in che presence of an F- substitutional impurity.