Detection and Correction of Delocalization Errors for Electron and Hole Polarons Using Density-Corrected DFT

Area of Science:

• Computational Materials Science
• Quantum Chemistry
• Solid-State Physics

Background:

• Modeling polaron defects is vital in computational materials science.
• Density functional theory (DFT) often struggles with delocalization error for unpaired spins.
• This error leads to inaccurate descriptions of spin defects.

Purpose of the Study:

• To implement and validate density-corrected DFT (DC-DFT) for accurate polaron defect modeling.
• To introduce an analytic energy gradient for DC-DFT.
• To diagnose and correct spin delocalization errors in materials.

Main Methods:

• Implementation of density-corrected DFT (DC-DFT).
• Evaluation of exchange-correlation functional using Hartree-Fock density.
• Calculation of analytic energy gradients for DC-DFT.
• Geometry optimization and single-point calculations on polarons in titania and Al-doped silica.

Main Results:

• DC-DFT successfully corrects spin delocalization errors.
• Geometry optimization with semilocal functionals causes significant structural distortions.
• Hybrid functionals may fail to localize polarons after semilocal optimization.
• DC-DFT identifies potential delocalization error issues in traditional workflows.

Conclusions:

• DC-DFT offers a robust approach to accurately model polaron defects.
• Standard DFT workflows using semilocal functionals can be misleading for spin defects.
• The developed DC-DFT method is essential for reliable computational materials science.
• Accurate defect modeling is critical for understanding and designing new materials.