CLUSTER MODELING OF METAL-OXIDES - THE INFLUENCE OF THE SURROUNDING POINT CHARGES ON THE EMBEDDED-CLUSTER

An ab initio study has been performed to investigate the influence of the surrounding point charges on the calculated electronic properties of the embedded NiO cluster. The employment of the nominal charges +/- 2.0 would cause overestimation of the crystal potential even for the so-called ionic oxide NiO. Several criteria, namely, the charge, poten tial, dipole moment and charge density consistence for determining the magnitude of point charges self-consistently have been proposed and e xamined. When the embedding point charges are spherically expanded, gi ving the embedding point charges a continuous distribution of charge d ensity, a good agreement is reached between the calculated properties of the embedded cluster model and those of the bulk solid after charge density consistence is fulfilled. (C) 1998 Elsevier Science B.V. All rights reserved.