ANALYSIS OF THE CONVERGENCE OF THE GENERAL COUPLING OPERATOR METHOD FOR ONE-CONFIGURATION-TYPE WAVE-FUNCTIONS

We comment on the convergence of the general coupling operator for all types of one-configuration or multiconfigurational wave functions tha t still preserve the one-configuration structure for the energy expres sion. The choice on the best arbitrary real and antisymmetric paramete rs inherent in the coupling operator methodology is discussed, giving a theoretical reason. Another type of coupling operator is defined, pr esented, and analyzed. Finally, we give some numerical examples relate d iu the low-lying electronic states of a cluster model for K2NiF4 sol id. (C) 1998 John Wiley & Sons, Inc.