Exchange-correlation potential built on the derivative discontinuity of electron density

TL;DR

This paper introduces a novel method for constructing exchange-correlation potentials in electronic structure calculations by leveraging the derivative discontinuity of electron density, leading to improved predictions of molecular properties.

Contribution

The work develops a first-principles approach to build XC potentials using a spatially dependent mixing parameter derived from the derivative discontinuity, with an approximation that enhances computational efficiency.

Findings

Accurately predicts ionization energies and fundamental gaps.

Provides reasonable estimates of singlet-triplet energy differences.

Potential for further improvement by removing the approximation.

Abstract

Electronic structures are fully determined by the exchange-correlation (XC) potential. In this work, we develop a new method to construct reliable XC potentials by properly mixing the exact exchange and the local density approximation potentials in real space. The spatially dependent mixing parameter is derived based on the derivative discontinuity of electron density and is first-principle. We derived the equations for solving the mixing parameter and proposed an approximation to simplify these equations. Based on this approximation, this new method gives reasonable predictions for the ionization energies, fundamental gaps, and singlet-triplet energy differences for various molecular systems. The impact of the approximation on the constructed XC potentials is examined, and it is found that the quality of the XC potentials can be further improved by removing the approximation. This work demonstrates that the derivative discontinuity of electron density is a promising constraint for constructing high-quality XC potentials.