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arXiv · 2205.10352

Impact of Retardation in the Holstein-Hubbard Model: a two-site Calculation

F. Marsiglio
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Abstract

Eliashberg theory provides a theoretical framework for understanding the phenomenon of superconductivity when pairing between two electrons is mediated by phonons, and retardation effects are fully accounted for. However, when a direct Coulomb interaction between two electrons is also present, this interaction is only partially accounted for. In this work we use a well-defined Hamiltonian, the Hubbard-Holstein model, to examine this competition more rigorously, using exact diagonalization on a two-site system. We find that the direct electron-electron repulsion between two electrons has a significantly more harmful effect on pairing than suggested through the standard treatment of this interaction.

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F. Marsiglio. 2022-05-06. Impact of Retardation in the Holstein-Hubbard Model: a two-site Calculation. https://arxiv.org/abs/2205.10352

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