Direct evidence of O(p) holes in Li-doped NiO from Hartree-Fock calculations

First-principles periodic Hartree-Fock calculations of the ground state electron distribution and empty oxygen p states in Li0.125Ni0.875O and Li0.25Ni0.75O are reported which provide direct evidence of oxygen p holes in Li-doped NiO. Calculated changes in the densities of empty oxygen p states are in good agreement with oxygen K-edge spectra. The empty states of the Li-doped materials provide a theoretical value of the band gap in NiO which, unlike previous estimates, is reasonably close to the observed value of 3.7 eV.