The Dual descriptor: physical bases and application to ground and low excited states

Abstract

The chemical reactivity can be related to the response of a molecule to an external perturbation. During the last three decades, chemical reactivity has been studied within the framework of density functional theory giving rise to a new field: conceptual DFT. This theory has proved quite successful in the understanding of the reactivity and the selectivity of chemical processes. In conceptual DFT the reactivity and the selectivity of a molecule is characterized through a set of descriptors raising from successive derivatives of the energy with respect to either the number of electron or the external potential. For selectivity issues, the key concept is generally the Fukui Functions. Those functions generalize within DFT the concept of Frontier Orbital introduced by K. FUKUI in the early sixties. Even though Fukui Functions are able to rediscover the main results already obtained using Frontier Molecular Orbital Theory, some important problems due to in-phase or out-of-phase interactions between orbitals are impossible to tackle The aim of this presentation is to introduce a three-dimensional function called « Dual Descriptor» or «Second Order Fukui Function»