ELECTRON CORRELATION STUDIES - RUMER BASIS APPROACH

A technique for the configuration interaction (CI) study of many-elect ron systems is developed based on Rumer spin-coupling scheme for the a ntisymmetrized configuration state functions (CSF). Incorporating a ne w graphical approach, the primitive configurations have been generated in blocks of definite ionocities to permit ready association of possi ble spin functions with each of the primitive configurations. Simple a s well as extended Hubard model Hamiltonians have been studied to test the efficiency of the method. Procedures have been incorporated to ca lculate various correlation functions using the spin-adapted CSFs with out invoking explicit expansions in terms of slater determinants. (C) 1996 John Wiley & Sons, Inc.