Eur. Phys. J. B 11, 551-557 (1999)
https://doi.org/10.1007/s100510051182

Small polaron formation in many-particle states of the Hubbard-Holstein model: The one-dimensional case

¹ Istituto Nazionale di Fisica della Materia and International School for Advanced Studies (SISSA-ISAS), Via Beirut 2-4, 34013 Trieste, Italy
² Istituto Nazionale di Fisica della Materia and Dipartimento di Fisica, Università di Roma "La Sapienza" , Piazzale A. Moro 2, 00185 Roma, Italy
³ Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada

Corresponding author: ^a capone@sissa.it

Received: 15 February 1999
Published online: 15 October 1999

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 . Numerically solving the model in a small one-dimensional cluster, we find that in the nearly adiabatic case , the necessary and sufficient condition for the polaronic regime to occur is that the energy gain in the atomic (i.e., extremely localized) regime overcomes the energy of the purely electronic system . In the antiadiabatic case, , polaron formation is instead driven by the condition of a large ionic displacement (g being the electron-phonon coupling). Dynamical properties of the model in the weak and moderately strong coupling regimes are also analyzed.