Embedding for bulk systems using localized atomic orbitals.

Area of Science:

• Computational materials science
• Condensed matter physics
• Quantum chemistry

Background:

• Point defects significantly influence semiconductor and insulator properties.
• Conventional methods like Kohn-Sham density functional theory face challenges in accurately modeling defect systems.
• Accurate theoretical treatment of defects is crucial for designing novel materials.

Purpose of the Study:

• To extend projection-based embedding techniques to bulk systems for accurate point defect calculations.
• To address non-additive kinetic energy contributions in defect modeling.
• To provide a robust computational tool for challenging defect systems.

Main Methods:

• Developed a density partition using orthogonal subsets of orbitals to avoid non-additive kinetic energy errors.
• Implemented the projection-based embedding method within the Vienna ab initio simulation package (VASP).
• Applied the method to study defect structures in silicon and polaron formation in titania.

Main Results:

• Successfully applied the method to model defect structures in silicon.
• Demonstrated accurate simulation of polaron formation in titania.
• Showcased the method's capability to handle challenging cases intractable for conventional DFT.

Conclusions:

• The extended projection-based embedding technique offers a powerful and accurate approach for studying point defects in bulk materials.
• This method overcomes key limitations of standard density functional theory for defect calculations.
• The implementation in VASP provides a practical tool for materials scientists and physicists.