Charged local defects in extended systems

Area of Science:

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

Background:

• First principles calculations are crucial for understanding materials.
• Treating charged defects in extended systems typically uses the supercell approximation with neutralizing jellium charge.
• This conventional method can introduce significant errors in the electrostatic potential.

Purpose of the Study:

• To quantify the errors in electrostatic potential caused by the conventional supercell approximation for charged defects.
• To present a novel method for accurately calculating the electrostatic potential around charged defects in supercell calculations.

Main Methods:

• Explicitly demonstrated errors in electrostatic potential surfaces for typical supercell sizes.
• Introduced a mixed boundary condition approach to eliminate Coulomb potential divergence.
• Applied the method to correctly treat the electrostatic potential in the local vicinity of charged defects.

Main Results:

• Errors in electrostatic potential can be comparable to the band gap energy in semiconductors.
• The proposed mixed boundary condition method effectively corrects potential divergence.
• Accurate treatment of the local electrostatic potential near charged defects is achieved.

Conclusions:

• The conventional supercell approximation with jellium charge introduces substantial errors in electrostatic potential calculations.
• The novel mixed boundary condition method provides a more accurate approach for simulating charged defects.
• This improved methodology enhances the reliability of first principles calculations for materials with charged defects.