Calculation of the dispersion interaction energy by using localized molecular orbitals

Abstract

In this paper, we present a method for the calculation of dispersion interaction energies of molecules, which is based on the localized molecular orbitals of the supermolecule. It is shown (using various basis sets) that the energy contributions of the localized molecular orbitals, for distances around the intermolecular energy minimum, are transferable to a fairly good approximation from the noninteracting monomers to the supermolecule. The correlation energy component of the interaction energy can be separated into inter- and intraparts. We show how the basis set superposition errors can be located and separated at the correlated level. Results are presented for several systems [(H2O)2, (NH3)2, and Ne2 ] with different basis sets from the minimal one to the split shell plus polarization functions. The method applies the well-known Boys’ localization procedure and has the advantage that for the dispersion energy at a given geometry, the integral transformation should only be carried out once (from the basis functions to the localized molecular orbitals of the supermolecule).