Fermi-Löwdin orbital self-interaction correction using the strongly constrained and appropriately normed meta-GGA functional

Abstract

Despite the success of density functional approximations (DFAs) in describing the electronic properties of many-electron systems, the most widely used approximations suffer from selfinteraction errors (SIE) that limit their predictive power. Here we describe the effects of removing SIE from the strongly constrained and appropriately normed (SCAN) meta-generalized gradient approximation (GGA) using the Fermi-Löwdin Orbital Self-Interaction Correction (FLOSIC) method. FLOSIC is a size-extensive implementation of the Perdew-Zunger self-interaction correction (PZ-SIC) formalism. We find that FLOSIC-SCAN calculations require careful treatment of numerical details and describe an integration grid that yields reliable accuracy with this approach.We investigate the performance of FLOSIC-SCAN for predicting a wide array of properties and find that it provides better results than FLOSIC-LDA and FLOSIC-PBE in nearly all cases. It also gives better predictions than SCAN for orbital energies and dissociation energies where selfinteraction effects are known to be important, but total energies and atomization energies are made worse. For these properties, we also investigate the use of the self-consistent FLOSIC-SCAN density in the SCAN functional and find that this DFA@FLOSIC-DFA approach yields improved results compared to pure, self-consistent SCAN calculations. Thus FLOSIC-SCAN provides improved results over the parent SCAN functional in cases where SIEs are dominant, and even when they are not, if the SCAN@FLOSIC-SCAN method is used. * a) rzope@utep.edu

Self-interaction error overbinds water clusters but cancels in structural energy differences

“…Recently, the Fermi-Löwdin orbital selfinteraction correction (FLOSIC) methodology (39,40) was introduced as an efficient and unitarily invariant approach for implementing PZ SIC that can be used in conjunction with any approximate XC functional. FLOSIC has been used to study properties of chemical and physical interest for a range of systems (41)(42)(43)(44)(45). Typically, both total error and SIE decrease from LDA to PBE to SCAN, but this is not always so.…”

Testing Self‐Interaction Correction for Molecules in Solution

“…[116,117] On the other hand, FLO-SIC and RSIC deliver MAEs slightly above 2.9 eV, which is larger than the errors that were reported from FLO-SIC calculations on various molecular test sets, ranging from 1.4 to 2.2 eV. [40,47,49,51] Apart from the effect of differing calculation parameters, the deviation of our result from the literature values can be explained at least in part by the fact that, with the exception of the water molecule, our AQUA20 test set does not intersect with the test sets of these prior studies. In fact, two of the prior studies mentioned earlier [40,51] already showed the test set dependency of the MAE, as each of them featured two different MAEs for two different test sets.…”

“…The DFT and FLO-SIC frameworks presented in the previous subsection are readily applied to isolated molecular systems, [16,30,[40][41][42][43][44][45][46][47][48][49][50][51] i.e., molecules under gas-phase conditions. However, as mentioned in Section 1, the simulation of molecules in solution requires a solvation model.…”

Importance of self-interaction-error removal in density functional calculations on water cluster anions

“…The Fermi orbitals are normalized, but are not othogonal. They are orthogonalized using Löwdin's method of symmetric orthonormalization 52 resulting in an orthonormal set of local orbitals called The Fermi-Löwdin orbital based self-interaction correction (FLO-SIC) method is implemented in the FLOSIC code 56,57 that is based on the UTEP-NRLMOL code 58,59 . This code uses a Gaussian basis set 60 , and a variational integration mesh 61 to perform numerically precise calculations on molecules composed of non-relativistic atoms.…”