Self-Interaction Error in Density Functional Theory: An Appraisal.

Area of Science:

• Quantum Chemistry
• Computational Physics
• Materials Science

Background:

• Self-interaction error (SIE) is a significant limitation in approximate exchange-correlation functionals within Kohn-Sham density-functional theory (KS-DFT).
• This error is particularly pronounced in local and some hybrid functionals, affecting accuracy for specific systems.

Purpose of the Study:

• To investigate the efficacy of multiconfiguration pair-density functional theory (MC-PDFT) in mitigating SIE for systems dominated by this error.
• To compare the performance of MC-PDFT with KS-DFT and CASSCF for SIE-prone systems.

Main Methods:

• Application of MC-PDFT using multiconfiguration self-consistent field (MCSCF) densities and on-top densities.
• Evaluation of error reduction for a translated local density-functional approximation within MC-PDFT.
• Comparison with standard KS-DFT calculations and complete active space self-consistent field (CASSCF).

Main Results:

• MC-PDFT significantly reduces SIE by a factor of 3 compared to KS-DFT when using MCSCF densities.
• MC-PDFT with local on-top functionals exhibits even lower errors, outperforming some popular KS-DFT hybrid functionals.
• Both MC-PDFT and certain KS-DFT hybrid functionals show smaller errors than CASSCF for SIE-prone systems.

Conclusions:

• MC-PDFT offers a promising approach to reduce self-interaction error in density-functional theory calculations.
• The method provides a more accurate description of electronic structure for systems where SIE is a dominant factor.
• MC-PDFT represents an advancement over traditional KS-DFT and CASSCF for specific challenging electronic systems.