# Noniterative Fermi–Löwdin Orbitals for Self-Interaction Correction

## TL;DR

This paper introduces a faster method for correcting self-interaction errors in quantum chemistry calculations, improving efficiency without losing accuracy.

## Contribution

The novel noniterative Fermi–Löwdin orbital self-interaction correction (NIFLOSIC) eliminates iterative relaxation of FODs.

## Key findings

- NIFLOSIC generates localized orbitals slightly more compact than grid-based methods.
- NIFLOSIC improves frontier molecular orbital energies and dipole moments significantly.
- NIFLOSIC reduces computational cost while reproducing results from fully self-consistent FLOSIC.

## Abstract

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.