A simple and efficient route towards improved energetics within the framework of density-corrected density functional theory

TL;DR

This paper introduces a simple, efficient indicator based on kinetic energy differences to determine when to replace DFT densities with Hartree-Fock densities, improving the energetics in density-corrected DFT calculations.

Contribution

It proposes a new kinetic energy indicator for density correction decision-making and a procedure to enhance functional accuracy by combining density correction with functional correction.

Findings

The indicator reliably identifies when HF density improves DFT results.

The procedure enhances the accuracy of density-corrected DFT calculations.

The method is computationally efficient and size-intensive.

Abstract

The crucial step in density-corrected Hartree-Fock density functional theory (DC(HF)-DFT) is to decide whether the density produced by the density functional for a specific calculation is erroneous and hence should be replaced by, in this case, the HF density. We introduce an indicator, based on the difference in non-interacting kinetic energies between DFT and HF calculations, to determine when the HF density is the better option. Our kinetic energy indicator directly compares the self-consistent density of the analysed functional with the HF density, is size-intensive, reliable, and most importantly highly efficient. Moreover, we present a procedure that makes best use of the computed quantities necessary for DC(HF)-DFT by additionally evaluating a related hybrid functional and, in that way, not only "corrects" the density but also the functional itself; we call that procedure corrected Hartree-Fock density functional theory (C(HF)-DFT).