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arXiv · 2310.01204

The multi-channel Dyson equation: coupling many-body Green's functions

Gabriele Riva·Pina Romaniello·J. Arjan Berger
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Abstract

We present the multi-channel Dyson equation that combines two or more many-body Green's functions to describe the electronic structure of materials. In this work we use it to model photoemission spectra by coupling the one-body Green's function with the three-body Green's function. We demonstrate that, unlike methods using only the one-body Green's function, our approach puts the description of quasiparticles and satellites on an equal footing. We propose a multi-channel self-energy that is static and only contains the bare Coulomb interaction, making frequency convolutions and self-consistency unnecessary. Despite its simplicity, we demonstrate with a diagrammatic analysis that the physics it describes is extremely rich. Finally, we present a framework based on an effective Hamiltonian that can be solved for any many-body system using standard numerical tools. We illustrate our approach by applying it to the Hubbard dimer and show that it is exact both at 1/4 and 1/2 filling.

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Gabriele Riva, Pina Romaniello, J. Arjan Berger. 2023-10-02. The multi-channel Dyson equation: coupling many-body Green's functions. https://arxiv.org/abs/2310.01204

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