The Fermi-Löwdin self-interaction correction for ionization energies of organic molecules

Santosh Adhikari, Biswajit Santra, Shiqi Ruan, Puskar Bhattarai, Niraj K. Nepal, Koblar A. Jackson, Adrienn Ruzsinszky

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(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 correction on 14 small to moderate-sized organic molecules relevant in organic electronics and polymer donor materials. Although 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 zσ, 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.

Original languageEnglish
Article number24776
JournalJournal of Chemical Physics
Issue number18
StatePublished - Nov 14 2020


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