Aperiodic defects in periodic solids

Area of Science:

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

Background:

• Traditional defect modeling uses periodic supercells, risking artifacts from defect image interactions.
• Charged or open-shell defects exacerbate issues, leading to slow convergence to the thermodynamic limit (TDL).

Purpose of the Study:

• To develop a novel computational method for defect modeling that overcomes limitations of periodic supercells.
• To achieve accurate and efficient simulations of defects, including charged and strongly correlated ones.

Main Methods:

• Introduced a "defectless" embedding formalism.
• Computed the embedding field in a pristine, primitive-unit-cell calculation.
• Incorporated a single, aperiodic defect within the embedded fragment, avoiding compensating background charges.

Main Results:

• Eliminated spurious artifacts and numerical issues associated with periodic defect modeling.
• Achieved very fast convergence to the thermodynamic limit (TDL).
• Enabled straightforward application of post-Hartree-Fock methods for complex defect studies.

Conclusions:

• The defectless embedding formalism provides a superior approach for accurate defect modeling.
• This method is particularly advantageous for charged, open-shell, and strongly correlated defects.
• It offers a robust framework for studying localized excited states and other challenging problems in materials science.