A density-division embedding potential inversion technique

Abstract

A method is proposed to partition the density of a system in two portions. The density on each subsystem is the solution of a Fock equation modified by the addition of an ``embedding'' potential. This embedding potential is obtained iteratively by minimizing the difference between the electronic densities of the total system and the sum of the subsystems. Thus, the electronic density partition and the two embedding potentials, one per portion, are obtained at the same time within the procedure, warranting the v-representability of the two densities obtained. The method is first applied to a linear H$_{10}$ chain to illustrate how it works. The orbitals obtained are localized on each subsystem, and can be used to include local electronic correlation using currently available {\it ab initio} programs. Finally, the method is applied to include the electronic correlation needed to describe the van der Waals interaction between H$_{10}$ chains and H$_2$ molecules, of $\approx$ 12 meV, giving very accurate results. Some preliminary results on the Br$_2$-H$_2$O will also be shown.