(Semi)-local density functional approximations (DFAs) suffer from self-interaction error (SIE). When the first ionization energy (IE) is computed as the negative of the highest-occupied orbital (HO) eigenvalue, DFAs notoriously underestimate them compared to quasi-particle calculations. The inaccuracy for the HO is attributed to SIE inherent in DFAs. We assessed the IE based on Perdew-Zunger self-interaction corrections on 14 small to moderate-sized organic molecules relevant in organic electronics and polymer donor materials. Though self-interaction corrected DFAs were found to significantly improve the IE relative to the uncorrected DFAs, they overestimate. However, when the self-interaction correction is interiorly scaled using a function of the iso-orbital indicator z{\sigma}, only the regions where SIE is significant get a correction. We discuss these approaches and show how these methods significantly improve the description of the HO eigenvalue for the organic molecules.
@article{arxiv.2008.05057,
title = {The Fermi-L\"owdin self-interaction correction for ionization energies of organic molecules},
author = {Santosh Adhikari and Biswajit Santra and Shiqi Ruan and Puskar Bhattarai and Niraj K. Nepal and Koblar A. Jackson and Adrienn Ruzsinszky},
journal= {arXiv preprint arXiv:2008.05057},
year = {2020}
}