Dissociation limit and the scaled-down self-interaction correction

The Perdew-Zunger self-interaction correction (PZ-SIC), when applied to a (semi)-local density functional approximation, removes spurious self-interaction error (SIE) on an orbital-by-orbital basis, making the functional exact for all one-electron systems. However, PZ-SIC is overcorrecting for many-electron systems. There were several schemes introduced in the past to scale-down PZ-SIC in many-electron regions. These so-called exterior scaling schemes were able to predict better equilibrium properties like atomization energies, first ionization energies, etc. compared to regular PZ-SIC. The problem of fractional-charge dissociation of heteronuclear molecules and charged molecular ions fixed by unscaled PZ-SIC methods returns with these exterior scalings. A recently introduced scheme [1] based on the interior scaling of PZ-SIC shows promising results for equilibrium properties like first ionization energies, electron affinities, atomization energies, barrier heights of chemical reactions, etc. In this work we are investigating the behavior of this recently proposed scheme on the dissociation of heteronuclear molecules.

[1] J. Chem Phys., 151, 21, 214108 (2019)