Electrostatics-based finite-size corrections for first-principles point defect calculations
Abstract
Finite-size corrections for charged defect supercell calculations typically consist of image-charge and potential alignment corrections. Regarding the image-charge correction, Freysoldt, Neugebauer, and Van de Walle (FNV) recently proposed a scheme that constructs the correction energy a posteriori through alignment of the defect-induced potential to a model charge potential [C. Freysoldt et al., Phys. Rev. Lett. 102, 016402 (2009), 10.1103/PhysRevLett.102.016402]. This, however, still has two shortcomings in practice. First, it uses a planar-averaged electrostatic potential for determining the potential offset, which can not be readily applied to defects with large atomic relaxation. Second, Coulomb interaction is screened by a macroscopic scalar dielectric constant, which can bring forth large errors for defects in layered and low-dimensional structures. In this study, we use the atomic site potential as a potential marker, and extend the FNV scheme by estimating long-range Coulomb interactions with a point charge model in an anisotropic medium. We also revisit the conventional potential alignment and show that it is unnecessary for correcting defect formation energies after the image-charge correction is properly applied. A systematic assessment of the accuracy of the extended FNV scheme is performed for defects and impurities in diverse materials: β-Li2TiO3, ZnO, MgO, Al2O3,HfO2, cubic and hexagonal BN, Si, GaAs, and diamond. Defect formation energies with -6 to +3 charges calculated using supercells containing around 100 atoms are successfully corrected even after atomic relaxation within 0.2 eV compared to those in the dilute limit.
- Publication:
-
Physical Review B
- Pub Date:
- May 2014
- DOI:
- 10.1103/PhysRevB.89.195205
- arXiv:
- arXiv:1402.1226
- Bibcode:
- 2014PhRvB..89s5205K
- Keywords:
-
- 61.72.J-;
- 71.15.Mb;
- 71.55.-i;
- Point defects and defect clusters;
- Density functional theory local density approximation gradient and other corrections;
- Impurity and defect levels;
- Condensed Matter - Materials Science
- E-Print:
- Phys. Rev. B 89, 195205 (2014)