Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Impact of Retardation in the Holstein-Hubbard Model: A Two-Site Calculation

Version 1 : Received: 10 May 2022 / Approved: 12 May 2022 / Online: 12 May 2022 (08:57:07 CEST)

How to cite: Marsiglio, F. Impact of Retardation in the Holstein-Hubbard Model: A Two-Site Calculation. Preprints 2022, 2022050165 (doi: 10.20944/preprints202205.0165.v1). Marsiglio, F. Impact of Retardation in the Holstein-Hubbard Model: A Two-Site Calculation. Preprints 2022, 2022050165 (doi: 10.20944/preprints202205.0165.v1).

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.

Keywords

Superconductivity; Holstein-Hubbard model; pseudopotential effect; retardation

Subject

PHYSICAL SCIENCES, Condensed Matter Physics

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