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arXiv · 2406.15629

Embedded multi-boson exchange: A step beyond quantum cluster theories

Dominik Kiese·Nils Wentzell·Igor Krivenko·Olivier Parcollet·Karsten Held·Friedrich Krien
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Abstract

We introduce a diagrammatic multi-scale approach to the Hubbard model based on the interaction-irreducible (multi-boson) vertex of a small cluster embedded in a self-consistent medium. The vertex captures short-ranged correlations up to the length scale of the cluster, while long-ranged correlations are recovered from a set of diagrammatic equations for the Hedin three-leg vertex. By virtue of the crossing symmetry, the Fierz decoupling ambiguity of the Hubbard interaction is resolved exactly. Our benchmarks for the half-filled Hubbard model on the square lattice are in very good agreement with numerically exact diagrammatic Monte Carlo simulations.

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Dominik Kiese, Nils Wentzell, Igor Krivenko, Olivier Parcollet, Karsten Held, Friedrich Krien. 2024-06-21. Embedded multi-boson exchange: A step beyond quantum cluster theories. https://arxiv.org/abs/2406.15629

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