Electron correlation studies: Rumer basis approach

Abstract

A technique for the configuration interaction (CI) study of many-electron systems is developed based on Rumer spin-coupling scheme for the antisymmetrized configuration state functions (CSF). Incorporating a new graphical approach, the primitive configurations have been generated in blocks of definite ionocities to permit ready association of possible spin functions with each of the primitive configurations. Simple as well as extended Hubard model Hamiltonians have been studied to test the efficiency of the method. Procedures have been incorporated to calculate various correlation functions using the spin-adapted CSFs without invoking explicit expansions in terms of slater determinants. (C) 1996 , Inc.