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
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.
PACS: 71.38.+i – Polarons and electron-phonon interactions / 63.20.Kr – Phonon-electron and phonon-phonon interactions / 71.10.Fd – Lattice fermion models (Hubbard model, etc.) / 71.27.+a – Strongly correlated electron systems; heavy fermions
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1999
