Electron-phonon coupling within Quasiparticle Self-consistent GW

The reliability of Density Functional Theory (DFT) for the electron-phonon coupling in many materials, including even simple sp-bonded compounds, has been questioned in recent years [1]. Hybrid functionals and quasiparticle GW corrections suggest that nonlocal exchange-correlation enhances the electron-phonon interaction [2-6] as a consequence of an improved description of the electronic screening. This has highlighted the need to move beyond local exchange-correlation functionals within DFT, but complete field-theoretic investigations are still missing in literature. In this talk I will introduce the development of a field-theoretic methodology which is able to predict on an equal footing electronic quasiparticles and phonons as well as their interaction. Such an approach has been implemented within the Quasiparticle Self-consistent GW (QSGW) formalism [7] which describes well the electronic properties for a wide range of materials [7], including many where standard DFT fails. The reliability of a such field-theoretic methodology will be discussed analyzing the renormalization of the optical gap of non polar semiconductors.

References:

[1] F. Giustino, Rev. Mod. Phys. 89, 015003 (2017).
[2] J. L. Janssen, et. al., Phys. Rev. B 81, 073106 (2010).
[3] Z. P. Yin, A. Kutepov, G. Kotliar, Phys. Rev. X 3, 021011 (2013).
[4] A. Floris, S. de Gironcoli, E. K. U. Gross, M. Cococcioni, Phys. Rev. B 84, 161102 (2011).
[5] M. Lazzeri, C. Attacalite, L. Wirtz, F. Mauri, Phys. Rev. B 78, 081406 (2008).
[6] G. Antonious, S. Poncé, P. Boulanger, M. Coté, X. Gonze, Phys. Rev. Lett. 112, 125501 (2014).
[7] T. Kotani, M. van Schilfgaarde, and S. V. Faleev, Phys, Rev. B 76, 165106 (2007).

Claudia Cardoso - claudia.cardoso@nano.cnr.it