Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 99: Electronic structure theory

HL 99.6: Vortrag

Donnerstag, 3. April 2014, 16:15–16:30, POT 151

Zero-point motion effect on the bandgap of diamond: validation of codes — •Samuel Poncé1, Gabriel Antonius2, Paul Boulanger3, Elena Cannuccia4, Andrea Marini5, Michel Côté2, and Xavier Gonze11UCL, 1348 LLN, Belgium — 2UMontréal, C.P. 6128, Montréal, Canada — 3Institut Néel, BP 166, 38042 Grenoble, France — 4ILL, BP 156 38042 Grenoble, France — 5CNR, CP 10, Mont. Stazione, Italy

Verification and validation of codes, as well as new theoretical methods, are of utmost importance if one wants to provide reliable results.

In this work we present a rigorous and careful study of all the quantities that enters into the calculation of the zero-point motion renormalization of the direct band gap of diamond due to electron-phonon coupling. This study has been done within the Allen-Heine-Cardona (AHC) formalism as implemented into Abinit and Yambo on top of Quantum Espresso. In this work we aim at quantifying the agreement between the codes for the different quantities of interest. This study shows that one can get less than 10−5Ha/at differences on the total energy, 0.07 cm−1 on the phonon frequencies, 0.5% on the electron-phonon matrix elements and less than 4 meV on the zero-point motion renormalization.

At the LDA level, the converged direct bandgap renormalization in diamond due to electron-phonon coupling in the AHC formalism is -409 meV (reduction of the bandgap)[1].

[1] S. Poncé et al., arXiv:1309.0729 [cond-mat.mtrl-sci] and submitted for publication in Comput. Mat. Science (2013).

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