Noniterative Fermi-Löwdin Orbitals for Self-Interaction Correction

We introduce the noniterative Fermi-Löwdin orbital self-interaction correction (NIFLOSIC) method as a computationally efficient alternative to traditional Fermi-Löwdin orbital self-interaction correction (FLOSIC) by eliminating the need for iterative relaxation of Fermi orbital descriptors (FODs). This is accomplished using the selected columns of the density matrix localization scheme [J. Chem. Theory Comput. 2023, 19, 8572] and by exploiting the relationship between the electron localization function and FODs [J. Chem. Phys. 2025, 162, 144105]. The approach produces localized orbitals that are slightly more compact than grid-based selected columns of the density matrix orbitals and generates FODs in a single, noniterative self-starting step, following density functional theory calculations. Within a generalized Kohn-Sham framework, full relaxation of the density minimizes the Perdew-Zunger energy functional, yielding self-interaction corrected densities and orbitals. NIFLOSIC reproduces results from fully self-consistent FLOSIC calculations, while significantly reducing computational cost. Although the total electronic energy is not suitable for thermochemistry, benchmark tests across diverse molecular systems demonstrate that NIFLOSIC significantly improves frontier molecular orbital energies and dipole moments, establishing a practical and scalable approach for large-scale electronic structure applications where self-interaction correction is needed.