Cluster calculation of oxygenK-edge electron-energy-loss near-edge structure of NiO

A first-principles molecular orbital calculation of NiO is made using a model cluster that includes a half-filled core hole. Major features of O K-edge electron energy loss near-edge structure up to 20 eV above the edge are satisfactorily reproduced simply by taking the O 2p partial density of states as a theoretical spectrum. Four peaks appeared in the experimental spectrum are well interpreted from the viewpoint of interactions among atomic orbital. Contrary to the previous multiple-scattering calculations, we found the major features in this energy range are determined within a smaller range, i.e., two Ni shells.