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Reproducibility in G0W0 calculations for solids

Abstract : Ab initio many-body perturbation theory within the GW approximation is a Green’s function formalism widely used in the calculation of quasiparticle excitation energies of solids. In what has become an increasingly standard approach, Kohn-Sham eigenenergies, generated from a DFT calculation with a strategically-chosen exchange correlation functional “starting point”, are used to construct G and W , and then perturbatively corrected by the resultant GW self-energy. In practice, there are several ways to construct the GW self-energy, and these can lead to variations in predicted quasiparticle energies. For example, for ZnO and TiO 2 , reported GW fundamental gaps can vary by more than 1 eV. In this work, we address the convergence and key approximations in contemporary G 0 W 0 calculations, including frequency-integration schemes and the treatment of the Coulomb divergence in the exact-exchange term. We study several systems, and compare three different GW codes: BerkeleyGW, Abinit and Yambo. We demonstrate, for the first time, that the same quasiparticle energies for systems in the condensed phase can be obtained with different codes, and we provide a comprehensive assessment of implementations of the GW approximation.
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https://hal-cea.archives-ouvertes.fr/cea-02927610
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Submitted on : Tuesday, September 1, 2020 - 6:02:01 PM
Last modification on : Saturday, October 10, 2020 - 3:07:38 AM

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Fabien Bruneval. Reproducibility in G0W0 calculations for solids. Computer Physics Communications, Elsevier, 2020, 255, pp.107242. ⟨10.1016/j.cpc.2020.107242⟩. ⟨cea-02927610⟩

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