Decomposition of electron density matrix and total energy of supermolecule in the method of non-orthogonal localized molecular orbitals

Abstract

The decomposition of the electron density matrix and the total energy of a supermolecule in the one-configuration approximation of the non-orthogonal localized molecular orbitals (NLMO) method based on the Frobenius block inversion formulae of the NLMO overlap matrix for two and many interacting subsystems was considered in terms of reduced one-particle density matrices of the subsystems. Formulae were derived which can be used as a theoretical basis for a qualitative and quantitative analysis of the coulombic, induction and exchange components of the intermolecular and intramolecular interaction energies and for the development of models of such interactions. This approach is related to the decomposition method developed by Morokuma and Umeyama, and to the method of non-orthogonal group functions of McWeeny and Dacre.