期刊
COMPUTATIONAL MATERIALS SCIENCE
卷 83, 期 -, 页码 341-348出版社
ELSEVIER
DOI: 10.1016/j.commatsci.2013.11.031
关键词
Density functional perturbation theory; Electron-phonon coupling; Temperature dependence; Verification; Allen-Heine-Cardona theory; Zero-point motion renormalization; Diamond
资金
- FRS-FNRS through a FRIA grant
- MIUR FIRB Grant [RBFR12SW0J]
- Fonds de la Recherche Scientifique de Belgique (FRS-FNRS)
With the ever-increasing sophistication of codes, the verification of the implementation of advanced theoretical formalisms becomes critical. In particular, cross comparison between different codes provides a strong hint in favor of the correctness of the implementations, and a measure of the (hopefully small) possible numerical differences. We lead a rigorous and careful study of the quantities that enter in the calculation of the zero-point motion renormalization of the direct band gap of diamond due to electron-phonon coupling, starting from the total energy, and going through the computation of phonon frequencies and electron-phonon matrix elements. We rely on two independent implementations: Quantum Espresso + Yambo and ABINIT. We provide the order of magnitude of the numerical discrepancies between the codes, that are present for the different quantities: less than 10(-5) Ha per atom on the total energy (-5.722 Ha/at), less than 0.07 cm(-1) on the C; L; X phonon frequencies (555-1330 cm(-1)), less than 0.5% on the square of the electron-phonon matrix elements and less than 4 meV on the zero-point motion renormalization of each eigenenergies (44-264 meV). Within our approximations, the DFT converged direct band gap renormalization in diamond due to the electron-phonon coupling is -0.409 eV (reduction of the band gap). (C) 2013 Elsevier B. V. All rights reserved.
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