Defect Formation Energies without the Band-Gap Problem: Combining DFT and GW for the Silicon Self-Interstitial

TL;DR

This paper introduces a combined DFT and GW approach to accurately compute defect formation energies in silicon, overcoming the band-gap problem and aligning well with experimental and high-level theoretical results.

Contribution

The paper presents a novel method that integrates DFT with G0W0 quasiparticle calculations to improve defect energy predictions in semiconductors.

Findings

G0W0 correction increases defect formation energy by ~1.1 eV.

G0W0 charge transition levels match experimental data.

Method reduces self-interaction errors in defect calculations.

Abstract

We present an improved method to calculate defect formation energies that overcomes the band-gap problem of Kohn-Sham density-functional theory (DFT) and reduces the self-interaction error of the local-density approximation (LDA) to DFT. We demonstrate for the silicon self-interstitial that combining LDA with quasiparticle energy calculations in the G0W0 approach increases the defect formation energy of the neutral charge state by ~1.1 eV, which is in good agreement with diffusion Monte Carlo calculations (E. R. Batista et al. Phys. Rev. B 74, 121102(R) (2006), W.-K. Leung et al. Phys. Rev. Lett. 83, 2351 (1999)). Moreover, the G0W0-corrected charge transition levels agree well with recent measurements.