Electron-Phonon Coupling from Ab Initio Linear-Response Theory within the GW Method: Correlation-Enhanced Interactions and Superconductivity in Ba_1-xK_xBiO₃

2019/02/28 by Zhenglu Li, Gabriel Antonius, Meng Wu +2 · 1 citation
Physics and Astronomy · #cond-mat.mtrl-sci

paper · pdf · doi:10.1103/physrevlett.122.186402

published as Phys. Rev. Lett. 122, 186402 (2019)

arxiv created 2019/05/13 · arxiv updated 2019/05/15

Abstract

We present a new first-principles linear-response theory of changes due to perturbations in the quasiparticle self-energy operator within the GW method. This approach, named GW perturbation theory (GWPT), is applied to calculate the electron-phonon (e-ph) interactions with the full inclusion of the GW non-local, energy-dependent self-energy effects, going beyond density-functional perturbation theory. Avoiding limitations of the frozen-phonon technique, GWPT gives access to e-ph matrix elements at the GW level for all phonons and scattering processes, and the computational cost scales linearly with the number of phonon modes (wavevectors and branches) investigated. We demonstrate the capabilities of GWPT by studying the e-ph coupling and superconductivity in Ba_0.6K_0.4BiO₃. We show that many-electron correlations significantly enhance the e-ph interactions for states near the Fermi surface, and explain the observed high superconductivity transition temperature of Ba_0.6K_0.4BiO₃ as well as its doping dependence.

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