Abstract
We investigate polaron formation in a many-electron system in the presence of a local repulsion sufficiently strong to prevent local-bipolaron formation. Specifically, we consider a Hubbard-Holstein model of interacting electrons coupled to dispersionless phonons of frequency ω 0. Numerically solving the model in a small one-dimensional cluster, we find that in the nearly adiabatic case ω 0 < t, the necessary and sufficient condition for the polaronic regime to occur is that the energy gain in the atomic (i.e., extremely localized) regime ε pol overcomes the energy of the purely electronic system ε el. In the antiadiabatic case, ω 0 > t, polaron formation is instead driven by the condition of a large ionic displacement g/ω 0 < 1 (g being the electron-phonon coupling). Dynamical properties of the model in the weak and moderately strong coupling regimes are also analyzed.
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Capone, M., Grilli, M. & Stephan, W. Small polaron formation in many-particle states of the Hubbard-Holstein model: The one-dimensional case. Eur. Phys. J. B 11, 551–557 (1999). https://doi.org/10.1007/BF03219179
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DOI: https://doi.org/10.1007/BF03219179