Verification and Validation of zero-point electron-phonon renormalization of the bandgap, mass enhancement, and spectral functions

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Hauptverfasser: Poncé, Samuel, Lihm, Jae-Mo, Park, Cheol-Hwan
Format: Preprint
Veröffentlicht: 2024
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author Poncé, Samuel
Lihm, Jae-Mo
Park, Cheol-Hwan
author_facet Poncé, Samuel
Lihm, Jae-Mo
Park, Cheol-Hwan
contents Verification and validation of methods and first-principles software are at the core of computational solid-state physics but are too rarely addressed. We compare four first-principles codes: Abinit, Quantum ESPRESSO, EPW, ZG, and three methods: (i) the Allen-Heine-Cardona theory using density functional perturbation theory (DFPT), (ii) the Allen-Heine-Cardona theory using Wannier function perturbation theory (WFPT), and (iii) an adiabatic non-perturbative frozen-phonon method. For these cases, we compute the real and imaginary parts of the electron-phonon self-energy in diamond and BAs, including dipoles and quadrupoles when interpolating. We find excellent agreement between software that implements the same formalism as well as good agreement between the DFPT and WFPT methods. Importantly, we find that the Deybe-Waller term is momentum dependent which impacts the mass enhancement, yielding approximate results when using the Luttinger approximations. Finally, we compare the electron-phonon spectral functions between Abinit and EPW and find excellent agreement even away from the band edges.
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publishDate 2024
record_format arxiv
spellingShingle Verification and Validation of zero-point electron-phonon renormalization of the bandgap, mass enhancement, and spectral functions
Poncé, Samuel
Lihm, Jae-Mo
Park, Cheol-Hwan
Materials Science
Verification and validation of methods and first-principles software are at the core of computational solid-state physics but are too rarely addressed. We compare four first-principles codes: Abinit, Quantum ESPRESSO, EPW, ZG, and three methods: (i) the Allen-Heine-Cardona theory using density functional perturbation theory (DFPT), (ii) the Allen-Heine-Cardona theory using Wannier function perturbation theory (WFPT), and (iii) an adiabatic non-perturbative frozen-phonon method. For these cases, we compute the real and imaginary parts of the electron-phonon self-energy in diamond and BAs, including dipoles and quadrupoles when interpolating. We find excellent agreement between software that implements the same formalism as well as good agreement between the DFPT and WFPT methods. Importantly, we find that the Deybe-Waller term is momentum dependent which impacts the mass enhancement, yielding approximate results when using the Luttinger approximations. Finally, we compare the electron-phonon spectral functions between Abinit and EPW and find excellent agreement even away from the band edges.
title Verification and Validation of zero-point electron-phonon renormalization of the bandgap, mass enhancement, and spectral functions
topic Materials Science
url https://arxiv.org/abs/2410.14319