SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 17: Mini-Symposium: Frontiers of electronic-structure theory: Focus on electron-phonon interactions I
O 17.1: Hauptvortrag
Montag, 1. März 2021, 13:30–14:00, R3
Predominance of non-adiabatic effects in zero-point renormalization of electronic energies — •Xavier Gonze1, 2, Anna Miglio1, Véronique Brousseau-Couture3, Gabriel Antonius4, 5, Yang-Hao Chan4, Steven Louie4, Bogdan Guster1, Matteo Giantomassi1, and Michel Côté3 — 1UCLouvain, Belgium — 2Skoltech, Moscow, Russia — 3U. de Montréal, Canada — 4U. California at Berkeley, USA and NBNL, Berkeley, USA — 5U. Québec à Trois-Rivières, Canada
Electronic and optical properties of materials are affected by atomic motion through electron-phonon interaction: not only band gaps change with temperature, but even at zero K, zero-point motion causes band-gap renormalization. We present a large-scale first-principles evaluation of the zero-point renormalization beyond the adiabatic approximation [1]. 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. We also investigate effective mass changes in such generalized Fröhlich model. [1] A. Miglio et al. npj Computational Materials, 6, 167 (2020).