Faddeev Random Phase Approximation for Molecules

TL;DR

The paper introduces the Faddeev RPA method for molecules, coupling electron motion with excitations, and demonstrates its effectiveness for diatomic molecules at equilibrium and during dissociation.

Contribution

It presents the first application of Faddeev RPA to molecules, extending beyond third-order methods by including phonon exchanges at the RPA level.

Findings

Successfully applied to diatomic molecules at equilibrium

Analyzed behavior during molecular dissociation

Retains all diagrams involving phonon exchange

Abstract

The Faddeev Random Phase Approximation is a Green's function technique that makes use of Faddeev-equations to couple the motion of a single electron to the two-particle--one-hole and two-hole--one-particle excitations. This method goes beyond the frequently used third-order Algebraic Diagrammatic Construction method: all diagrams involving the exchange of phonons in the particle-hole and particle-particle channel are retained, but the phonons are described at the level of the Random Phase Approximation. This paper presents the first results for diatomic molecules at equilibrium geometry. The behavior of the method in the dissociation limit is also investigated.