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

• Published in: npj computational materials Vol. 6; no. 1
• Main Authors: Miglio, Anna, Brousseau-Couture, Véronique, Godbout, Emile, Antonius, Gabriel, Chan, Yang-Hao, Louie, Steven G., Côté, Michel, Giantomassi, Matteo, Gonze, Xavier
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 06-11-2020; Nature Publishing Group
• Subjects: 639/301/1034/1038; 639/301/119/995; Absolute zero; Adiabatic; Adiabatic flow; Characterization and Evaluation of Materials; Chemistry and Materials Science; Computational Intelligence; Energy gap; First principles; Light elements; Material properties; MATERIALS SCIENCE; Mathematical and Computational Engineering; Mathematical and Computational Physics; Mathematical Modeling and Industrial Mathematics; Optical properties; Phonons; Theoretical
• ISSN: 2057-3960; 2057-3960
• DOI: 10.1038/s41524-020-00434-z

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.