How well do one-electron self-interaction-correction methods perform for systems with fractional electrons?

Area of Science:

• Quantum Chemistry
• Computational Materials Science
• Electronic Structure Theory

Background:

• Self-interaction error is a significant problem in density functional theory (DFT) approximations.
• The Perdew-Zunger self-interaction correction (PZSIC) method attempts to correct this error but exhibits paradoxical behavior.
• The locally scaled self-interaction correction (LSIC) is a newer, one-electron SIC method designed to improve upon PZSIC.

Purpose of the Study:

• To evaluate the performance of the LSIC method in mitigating delocalization errors.
• To compare the accuracy of LSIC against PZSIC for various electronic structure problems.
• To assess the ability of LSIC to describe molecular dissociation and fractional charges.

Main Methods:

• The study employed the LSIC method with a ratio of kinetic energy densities (zσ) as an iso-orbital indicator.
• Calculations were performed for molecular dissociation (H2+, He2+, LiF) and vertical ionization energies.
• The linearity of energy versus electron number curves for fractional charges was analyzed.

Main Results:

• Both LSIC and PZSIC accurately describe the dissociation of H2+ and He2+, with LSIC showing higher overall accuracy.
• Neither LSIC nor PZSIC exhibited delocalization errors for the vertical ionization energy of isolated He atoms.
• Both methods significantly reduced deviations from linearity for fractional charges, with PZSIC being superior for C, Ne, and Ar.
• LSIC demonstrated accurate charge transfer in LiF dissociation, aligning with experimental and ab initio data.

Conclusions:

• The LSIC method substantially reduces delocalization errors in electronic structure calculations.
• LSIC offers improved accuracy and better description of charge transfer compared to PZSIC in specific cases.
• LSIC shows promise as a robust method for accurate electronic structure predictions.