Non-linear response in the cumulant expansion for core hole photoemission

Abstract

Most currently used approximations for the one-particle Green's function G in the framework of many-body perturbation theory, such as Hedin's GW approximation or the cumulant GW+C approach, are based on a linear response approximation for the screened interaction W. The extent to which such a hypothesis is valid and ways to go beyond have been explored only very little. Here we show how to derive a cumulant Green's function beyond linear-response from the equation of motion of the Green's function in a functional derivative formulation. The results can be written in a compact form, which opens the possibility to calculate the corrections in a first principles framework using time-dependent density functional theory. In order to illustrate the potential importance of the corrections, numerical results are presented for a model system with a core level and two valence orbitals.

9 pages, 1 figure

References in corpus (4)

• Beyond the GW approximation: combining correlation channels
• Satellite Band Structure in Silicon Caused by Electron-Plasmon Coupling
• Theory of electron-plasmon coupling in semiconductors
• Real time cumulant approach for charge transfer satellites in x-ray photoemission spectra

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