Effect of discontinuities in Kohn-Sham-based chemical reactivity theory

TL;DR

This paper derives a new formula for the Fukui function in density-functional reactivity theory that accounts for Kohn-Sham system discontinuities, highlighting the role of the exchange-correlation kernel in chemical reactivity analysis.

Contribution

It introduces a novel derivation of the Fukui function formula that incorporates Kohn-Sham discontinuities and emphasizes the importance of the XC kernel's discontinuity for accurate reactivity measurement.

Findings

Discontinuities in the Kohn-Sham system affect the Fukui function.

The XC kernel's discontinuity is crucial for correct reactivity assessment.

Model systems demonstrate the significance of these discontinuities.

Abstract

We provide a new derivation of a formula for the Fukui function of density-functional chemical reactivity theory which incorporates the discontinuities in the Kohn-Sham reference system. Orbital relaxations are described in terms of the exchange-correlation (XC) kernel, i.e., the derivative of the XC potential with respect to the density and it is shown that in order to correctly measure the reactivity toward a nucleophilic reagent a discontinuity of the XC kernel has to be taken into account. The importance of this finding is illustrated in model molecular systems.