Self-interaction corrected Kohn-Sham effective potentials using the density-consistent effective potential method

TL;DR

This paper introduces a method to correct self-interaction errors in Kohn-Sham potentials within DFT, improving the accuracy of electronic structure predictions like ionization energies and spectra.

Contribution

The authors adapt and implement the density-consistent effective potential (DCEP) method for self-interaction correction in the FLOSIC scheme, enhancing the accuracy of electronic properties.

Findings

Good agreement with experimental ionization energies

Accurate density of states and HOMO-LUMO gaps

Improved results over uncorrected density functionals

Abstract

Density functional theory (DFT) and beyond-DFT methods are often used in combination with photoelectron spectroscopy to obtain physical insights into the electronic structure of molecules and solids. The Kohn-Sham eigenvalues are not electron removal energies except for the highest occupied orbital. The eigenvalues of the highest occupied molecular orbitals often underestimate the electron removal or ionization energies due to the self-interaction (SI) errors in approximate density functionals. In this work, we adapt and implement the density-consistent effective potential(DCEP) method of Kohut, Ryabinkin, and Staroverov to obtain SI corrected local effective potentials from the SI corrected Fermi-L\"owdin orbitals and density in the FLOSIC scheme. The implementation is used to obtain the density of states (photoelectron spectra) and HOMO-LUMO gaps for a set of molecules and polyacenes. Good agreement with experimental values is obtained compared to a range of SI uncorrected density functional approximations.