Relation between image charge and potential alignment corrections for charged defects in periodic boundary conditions

Area of Science:

• Computational materials science
• Solid-state physics
• Quantum chemistry

Background:

• Periodic density functional theory (DFT) is widely used for studying charged defects.
• DFT calculations suffer from significant finite-size artifacts due to the artificial periodicity of supercells.
• Existing methods struggle to accurately correct for these artifacts, limiting predictive power.

Purpose of the Study:

• To develop a robust electrostatic image interaction correction (IIC) method for charged defects in DFT.
• To investigate and decompose the sources of potential alignment in supercell calculations.
• To provide a theoretical framework for understanding and mitigating finite-size effects in defect studies.

Main Methods:

• Developed a novel electrostatic image interaction correction (IIC) method solving the Poisson equation for DFT-derived charge models.
• Introduced a decomposition technique to separate contributions to potential alignment.
• Analyzed the influence of defect image interactions and supercell atomic composition on potential alignment.

Main Results:

• The developed IIC method is largely insensitive to atomic details, depending primarily on bulk dielectric properties.
• Defect image interactions are accurately predicted by the periodic component of the IIC.
• Changes in supercell atom count significantly impact finite-size dependence, varying between defect types (e.g., vacancies vs. interstitials).
• Atomic radius and pseudopotential choice influence the correction for supercell size effects.

Conclusions:

• The developed IIC method, combined with potential alignment corrections, offers accurate mitigation of finite-size effects for charged defects in DFT.
• The decomposition provides a new theoretical basis for established finite-size scaling rules.
• The findings enable more reliable predictions of defect properties in materials using periodic DFT.