Local Spin Density Approximation Strongly Improved by a Better-Informed Local Scaling of Its Self-Interaction...

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Materials Science

Background:

• Density Functional Approximations (DFAs) are crucial for electronic structure calculations.
• The Perdew-Zunger self-interaction correction (PZSIC) improves DFAs but overcorrects in many-electron regions.
• Locally Scaled PZSIC (LSIC) corrects PZSIC errors for uniform densities but struggles with weakly bonded systems.

Purpose of the Study:

• To develop an improved self-interaction correction method that accurately describes both uniform and non-uniform electron densities.
• To enhance the description of weakly bonded systems within DFAs.
• To refine density functional approximations for a wider range of chemical and physical properties.

Main Methods:

• Introduction of LSIC-α, a new local scaling method based on the iso-orbital indicator α_σ.
• Fitting a two-parameter scaling function of α_σ for SCAN and r²SCAN meta-GGAs.
• Testing LSIC-α on properties of main-group atoms, molecules, and molecular complexes, including S22 dataset.

Main Results:

• LSIC-α significantly improves interaction energies for weakly bonded systems.
• The method retains the accuracy of LSIC for other chemical properties.
• LSIC-α demonstrates a substantial, though not complete, repair of self-interaction errors in DFAs.

Conclusions:

• LSIC-α offers a more robust self-interaction correction for DFAs, particularly for van der Waals interactions.
• The use of α_σ effectively identifies and corrects errors in overlapping density tail regions.
• This work advances the development of accurate and reliable DFAs for diverse chemical applications.