Fermi-Löwdin self-interaction correction for ground and excited states*

Self-interaction error (SIE) is strongly present in ground-state density functional theory (DFT) and propagates into time-dependent DFT as well. A significant requirement of the self-interaction correction (SIC) is the localization of the orbitals, as required by size-consistency. In 2014, Pederson and collaborators recommended a computationally much more attractive version of the earlier Perdew-Zunger (PZ) SIC [1]. This SIC utilizes Fermi orbitals, greatly restricting the number of possible unitary transformations of the occupied Kohn-Sham orbitals. This work is a straightforward continuation of the Fermi orbital PZ-SIC to test crucial physical properties relevant for both ground, and excited states, with the potential to eliminate SIE for excitation energies.

[1] M.R. Pederson, A. Ruzsinszky, and J.P. Perdew, J. Chem. Phys. 140, 121103 (2014)