http://www.cnr.it/ontology/cnr/individuo/prodotto/ID738

Dynamical mean field theory of polarons and bipolarons in the half-filled Holstein model (Articolo in rivista)

Type

Prodotto della ricerca (Classe)
Articolo in rivista (Classe)

Label

Dynamical mean field theory of polarons and bipolarons in the half-filled Holstein model (Articolo in rivista) (literal)

Anno

2006-01-01T00:00:00+01:00 (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi

10.1103/PhysRevB.74.045106 (literal)

Alternative label

M. Capone (1); P. Carta (2); S. Ciuchi (3) (2006)
Dynamical mean field theory of polarons and bipolarons in the half-filled Holstein model
in Physical review. B, Condensed matter and materials physics
(literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori

M. Capone (1); P. Carta (2); S. Ciuchi (3) (literal)

Pagina inizio

045106 (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#url

http://link.aps.org/doi/10.1103/PhysRevB.74.045106 (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume

74 (literal)

Rivista

Physical review. B, Condensed matter and materials physics (Rivista)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#pagineTotali

18 (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroFascicolo

4 (literal)

Note

ISI Web of Science (WOS) (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni

(1) INFM-SMC and Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, Via dei Taurini 19, I-00185 Rome, Italy and Dipartimento di Fisica, Universitá di Roma \"La Sapienza,\" Piazzale A. Moro 2, I-00185, Rome (2) Università degli Studi di Cagliari, Dipartimento di Fisica and INFN, Sezione di Cagliari, Cittadella Universitaria I-09042, Monserrato, Italy (3) ISC-CNR and Dipartimento di Fisica, Università de L'Aquila, 67010 Coppito-L'Aquila, Italy (literal)

Titolo

Dynamical mean field theory of polarons and bipolarons in the half-filled Holstein model (literal)

Abstract

The evolution of the properties of a finite density electronic system as a function of the electron-phonon coupling is investigated in the Holstein model using the dynamical mean-field theory (DMFT) that becomes exact in infinite dimensions. We compare the spinless fermion case, in which only isolated polarons can be formed, with the spinful model in which the polarons can bind and form bipolarons. In the latter case, the bipolaronic binding occurs within DMFT as a metal-insulator transition. In the adiabatic regime in which the phonon energy is small with respect to the electron hopping we compare numerically exact DMFT results with an analytical scheme inspired by the Born-Oppenheimer procedure. Within the latter approach, a truncation of the phononic Hilbert space leads to a mapping of the original model onto an Anderson spin-fermion model. In the anti-adiabatic regime (where the phonon energy exceeds the electronic scales) the standard treatment based on Lang-Firsov canonical transformation allows one to map the original model on to an attractive Hubbard model in the spinful case. The separate analysis of the two regimes supports the numerical evidence that the presence of well-defined polaronic lattice displacements is not necessarily associated to a metal-insulator transition, which is instead due to pairing between the carriers. The finite-dimensionality effects neglected in DMFT may lead to a finite conductivity in the bipolaronic state which is, however, not always associated with polaronic distortions. At the polaron crossover the Born-Oppenheimer approximation is shown to break down due to the entanglement of the electron-phonon state. (literal)

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