Generalized Fröhlich model vs accurate first-principles: zero-point renormalisation in polar semiconductors and insulators.

ORAL

Abstract

Computing the zero-point renormalization (ZPR) of the electronic bandgap due to electron-phonon coupling from first principles (FP) is a computationaly challenging task, especially for polar materials, for which a very fine phonon wavevector sampling is required [1]. By contrast, the well-known Fröhlich Hamiltonian gives in the perturbative regime a simple analytical formula for the polaron binding energy, based on a few parameters that can be obtained from experiments or from FP calculations.

We compute the ZPR from FP for more than 20 polar binary semiconductors and insulators, and compare these results to those from a generalized Fröhlich model, in which the needed parameters are computed from FP. Despite the lack of Debye-Waller (DW) and interband contributions, we find that the simple Fröhlich approach agrees with FP results within a factor of two for most materials. We analyze the cancellation between the DW and Fan contributions from acoustic modes, and discuss the size of interband contributions in terms of Eliashberg functions. We finally develop a method to estimate the converged ZPR from coarser phonon samplings.

[1] G. Antonius et al, PRB 92, 085137 (2015); S. Poncé et al, J. Chem. Phys. 143, 102813 (2015).

*NSERC grants RGPIN2016-06666, Calcul Québec and Compute Canada.

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Presenters

  • Véronique Brousseau-Couture

    • Université de Montréal and RQMP, Montréal, Québec, Canada

Authors

  • Véronique Brousseau-Couture

    • Université de Montréal and RQMP, Montréal, Québec, Canada

  • Anna Miglio

    • Université Catholique de Louvain, IMCN/NAPS , Louvain-la-Neuve, Belgium
    • IMCN, Université catholique de Louvain

  • Matteo Giantomassi

    • Universite catholique de Louvain
    • Université catholique de Louvain
    • Université Catholique de Louvain, IMCN/NAPS , Louvain-la-Neuve, Belgium

  • Gabriel Antonius

    • Département de Chimie, Biochimie et Physique, Université du Québec à Trois-Rivières
    • Department of Physics, University of California at Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory
    • University of California, Berkeley
    • Department of Physics, University of California at Berkeley, California 94720, USA, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 9

  • Yang-Hao Chan

    • Department of Physics, University of California at Berkeley, California 94720, USA and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, Californi
    • Lawrence Berkeley National Lab and University of California, Berkeley

  • Michel Cote

    • RQMP, Université de Montréal
    • Université de Montréal and RQMP
    • Université de Montréal and RQMP, Montréal, Québec, Canada
    • Universite de Montreal

  • Xavier Gonze

    • Université catholique de Louvain
    • Université Catholique de Louvain, IMCN/NAPS , Louvain-la-Neuve, Belgium
    • IMCN, Université catholique de Louvain
    • Universite catholique de Louvain