FRAGMENT CALCULATION OF ELECTRONIC-STRUCTURES OF POLYATOMIC-MOLECULESIN THE GROUND-STATE .1. A METHOD OF INTERMEDIATE FRAGMENT

A method is proposed for fragment calculation of electronic structures of polyatomic molecules in the ground state. The wave function of a m olecule in the ground stare in single-determinantal representation of a closed shell is employed. The concise formulation allows efficient c alculation of the electronic structures of polyatomic molecules taking into account possible charge transfer between interacting molecular f ragments.