Predominance of non-adiabatic effects in zero-point renormalization of the electronic band gap

Anna Miglio, Véronique Brousseau-Couture, Emile Godbout, Gabriel Antonius, Yang Hao Chan, Steven G. Louie, Michel Côté, Matteo Giantomassi, Xavier Gonze

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)

Abstract

Electronic and optical properties of materials are affected by atomic motion through the electron–phonon interaction: not only band gaps change with temperature, but even at absolute zero temperature, zero-point motion causes band-gap renormalization. We present a large-scale first-principles evaluation of the zero-point renormalization of band edges beyond the adiabatic approximation. For materials with light elements, the band gap renormalization is often larger than 0.3 eV, and up to 0.7 eV. This effect cannot be ignored if accurate band gaps are sought. For infrared-active materials, global agreement with available experimental data is obtained only when non-adiabatic effects are taken into account. They even dominate zero-point renormalization for many materials, as shown by a generalized Fröhlich model that includes multiple phonon branches, anisotropic and degenerate electronic extrema, whose range of validity is established by comparison with first-principles results.

Original languageEnglish
Article number167
Journalnpj Computational Materials
Volume6
Issue number1
DOIs
Publication statusPublished - 1 Dec 2020

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