A regional embedding method

Abstract

AbstractA new variational embedding method is derived. This method couples Nesbet's use of theR‐matrix in the determination of the electronic structure of a crystal with the energy variational technique. The procedure is based on the observation that in many cases the properties for a spatial region of a system change by relatively small amounts when the region is transferred to another system. The transfer of the region from one system to another is accomplished by the embedding potential that is obtained by the inversion of theR‐matrix and its energy derivative. It is shown that the interaction between two connected regions can be written as a surface term that is obtained by the continuity conditions on the wave function and its derivative on the surface. The existence of an identity resolution on the surface is demonstrated and this result is used to derive theR‐matrix and its inverse. An application of this method to His given, which shows that the method is accurate and reliable if one chooses the appropriate basis set to construct theR‐matrix and to perform the variation. © 1992 John Wiley & Sons, Inc.