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| Main Authors: | , , , , |
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| Format: | Preprint |
| Published: |
2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2501.04176 |
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| _version_ | 1866909451092492288 |
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| author | Riva, Gabriele Fischer, Théodore Paggi, Stefano Berger, J. Arjan Romaniello, Pina |
| author_facet | Riva, Gabriele Fischer, Théodore Paggi, Stefano Berger, J. Arjan Romaniello, Pina |
| contents | We extend the concept of the multichannel Dyson equation that we have recently derived to model photoemission spectra by coupling the one- and the three-body Green's functions, to higher-order Green's functions and to other spectroscopies. We show the general structure of the equations and how one can systematically approximate the corresponding multichannel self-energy. As a particular case, we focus on the coupling of the two-body and the four-body Green's functions in the electron-hole channel to describe neutral excitations. This formulation allows for the description of important many-body effects, such biexcitons, in a natural way. We illustrate our approach by applying it to a two-level model system, which, in a one-particle picture, exhibits single and double excitations. Our method can correctly describe both kinds of excitation, unlike standard approaches, and in good agreement with the exact results. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2501_04176 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Multichannel Dyson equations for even- and odd-order Green's functions: application to double excitations Riva, Gabriele Fischer, Théodore Paggi, Stefano Berger, J. Arjan Romaniello, Pina Strongly Correlated Electrons We extend the concept of the multichannel Dyson equation that we have recently derived to model photoemission spectra by coupling the one- and the three-body Green's functions, to higher-order Green's functions and to other spectroscopies. We show the general structure of the equations and how one can systematically approximate the corresponding multichannel self-energy. As a particular case, we focus on the coupling of the two-body and the four-body Green's functions in the electron-hole channel to describe neutral excitations. This formulation allows for the description of important many-body effects, such biexcitons, in a natural way. We illustrate our approach by applying it to a two-level model system, which, in a one-particle picture, exhibits single and double excitations. Our method can correctly describe both kinds of excitation, unlike standard approaches, and in good agreement with the exact results. |
| title | Multichannel Dyson equations for even- and odd-order Green's functions: application to double excitations |
| topic | Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2501.04176 |