P-297

Nery, Telma de Cassia dos Santos; Christensen, Rogerio

doi:10.1097/01.ede.0000417299.11580.b5

Cited by 1 publication

(3 citation statements)

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“…3(b) we repeat the calculations, this time using 4 distinct configurations, according to Eqs. (5), (12), and (13). Here we see that increasing the number of atomic configurations suppresses spurious fluctuations in the spectra; the effect is most pronounced for the smallest supercell, which corresponds to 2 × 2 × 2 Si unit cells.…”

Section: Improvements Using Configurational Averagingmentioning

confidence: 66%

“…(b) Comparison between calculations performed using a single configuration as in (a) (red solid lines), and those performed using 4 configurations, as specified by Eqs. (5),(12), and(13). The curves corresponding to the 8 × 8 × 8 supercell have been rigidly shifted by 0.1 eV: without such a shift the curves would overlap with those obtained using a 4 × 4 × 4 supercell.…”

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confidence: 89%

“…Recently it was pointed out that, in the case of polar semiconductors, calculations based on the Allen-Heine theory exhibit a spurious divergence when the quasiparticle lifetimes are set to zero. 10,13 The origin of this artifact relates to the Frölich electron-phonon coupling, 61,62 and has been discussed in Ref. 20.…”

Section: Direct Semiconductors: Gallium Arsenidementioning

confidence: 99%

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One-shot calculation of temperature-dependent optical spectra and phonon-induced band-gap renormalization

2016

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Recently, Zacharias et al. [Phys. Rev. Lett. 115, 177401 (2015)] developed a new ab initio theory of temperature-dependent optical absorption spectra and band gaps in semiconductors and insulators. In that work the zero-point renormalization and the temperature dependence were obtained by sampling the nuclear wavefunctions using a stochastic approach. In the present work, we show that the stochastic sampling of Zacharias et al. can be replaced by fully deterministic supercell calculations based on a single optimal configuration of the atomic positions. We demonstrate that a single calculation is able to capture the temperature-dependent band gap renormalization including quantum nuclear effects in direct-gap and indirect-gap semiconductors, as well as phonon-assisted optical absorption in indirect-gap semiconductors. In order to demonstrate this methodology we calculate from first principles the temperature-dependent optical absorption spectra and the renormalization of direct and indirect band gaps in silicon, diamond, and gallium arsenide, and we obtain good agreement with experiment and with previous calculations. In this work we also establish the formal connection between the Williams-Lax theory of optical transitions and the related theories of indirect absorption by Hall, Bardeen, and Blatt, and of temperature-dependent band structures by Allen and Heine. The present methodology enables systematic ab initio calculations of optical absorption spectra at finite temperature, including both direct and indirect transitions. This feature will be useful for high-throughput calculations of optical properties at finite temperature, and for calculating temperature-dependent optical properties using high-level theories such as GW and Bethe-Salpeter approaches.

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Section: Improvements Using Configurational Averagingmentioning

confidence: 66%

mentioning

confidence: 89%