Simplification of the Fermi-L\"owdin Self-Interaction Correction Method for Efficient Self-Interaction-Free Density Functional Calculations

TL;DR

This paper introduces a simplified FLOSIC method called vSOSIC that reduces computational cost by focusing on selected orbitals, achieving comparable accuracy to traditional SIC methods and improving efficiency in calculations.

Contribution

The authors propose a valence-focused SOSIC approach that simplifies FLOSIC calculations, making them faster and smoother while maintaining accuracy for various properties.

Findings

vSOSIC achieves similar accuracy to full FLOSIC for most properties.

The method significantly reduces computational time and complexity.

vSOSIC provides a reliable alternative to high-level methods like CCSD(T) for certain properties.

Abstract

Fermi-L\"owdin orbital self-interaction-correction (FLOSIC) method uses symmetric orthogonalized Fermi orbitals as localized orbitals in one-electron SIC schemes. In FLOSIC, a set of Fermi orbital descriptors (FOD) that define the FLOs is obtained by energy minimization. Determination of optimal FODs is a computationally very demanding task. Here, we propose to simplify the FLOSIC calculations by removing self-interaction error (SIE) from a set of selected orbitals of interest (SOSIC). We illustrate the approach by choosing a set of valence orbitals as active orbitals in SOSIC. The results of a wide range of properties obtained using the valence SOSIC (vSOSIC) scheme are compared with those obtained with the Perdew-Zunger SIC. The two methods agree within a few percent for the majority of the properties. The mean absolute error in the vertical detachment energy of water cluster anions with vSOSIC-PBE against benchmark CCSD(T) results is only 15 meV making vSOSIC-PBE an excellent alternative to the CCSD(T) for the case. The calculation on the [Cu$_2$Cl$_6$]$^{2-}$ complex demonstrates that the FOD optimization in vSOSIC is substantially smoother and faster. Assessment of the performance of SIC-r$^2$SCAN shows that it performs similarly to the SIC-SCAN for most properties, but for atomization energies, SIC-r$^2$SCAN outperforms SIC-SCAN.