Assisting the performance of self-interaction-corrected SCAN meta-GGA functional using an orbital scaling approach

Semilocal density functional approximations (DFAs) suffer from self-interaction (SI) error which limits their applicability. The Perdew-Zunger SI correction (PZSIC) improves the description of properties such as barrier heights or dissociation energies where SI error is dominant but it degrades already good performance of DFAs when applied to GGA and meta-GGA functionals. We implemented the orbital scaling approach of Vydrov et al.[1] that scales down orbital wise PZSIC in the FLOSIC code and use it with SCAN functional to assess its performance for a wide range of properties such as total energies, ionization potentials, and electron affinities for atoms, and atomization energies, dissociation and reaction energies, and reaction barrier heights of molecules. Our results show that orbital scaling recovers the performance of SCAN that is lost with SIC. We suggest a modification to recover -1/r asymptotic behavior of the potential lost by the scaling scheme of Vydrov et al. We also discuss the cases where the orbital scaling is not successful. General strategies of applying the scaling and how to improve its performance will be discussed in this talk.

[1] Vydrov et al. J. Chem. Phys. 124, 094108 (2006).