Cluster modeling of solid state defects and adsorbates: Beyond the hartree–fock level

The use of finite clusters of atoms to represent the physically interesting portion of a condensed matter system has been an accepted technique for the past two decades. Physical systems have been studied in this way using both density functional and Hartree–Fock methodologies, as well as a variety of empirical or semiempirical techniques. In this article, the author concentrates on the Hartree–Fock based methods. The attempt here is to construct a theoretical basis for the inclusion of correlation corrections in such an approach, as well as a strategy by which the limits of a finite cluster may be transcended in such a study. The initial appeal will be to a modeling approach, but methods to convert the model to a self‐contained theory will be described. It will be seen for the case of diffusion of large ions in solids that such an approach is quite useful. A further study of the case of adsorption of rare gas atoms on simple metals will demonstrate the value of inclusion of electron correlation