Physics – Condensed Matter – Strongly Correlated Electrons
Scientific paper
2005-09-21
Phys. Rev. B 74, 045106 (2006)
Physics
Condensed Matter
Strongly Correlated Electrons
19 pages, 15 figures
Scientific paper
10.1016/j.physb.2005.01.236
The evolution of the properties of a finite density electronic system as the electron-phonon coupling is increased are investigated in the Holstein model using the Dynamical Mean-Field Theory (DMFT). 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 through 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 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 polaron formation is not necessarily associated to a metal-insulator transition, which is instead due to pairing between the carriers. At the polaron crossover the Born-Oppenheimer approximation is shown to break down due to the entanglement of the electron-phonon state.
Capone Massimo
Carta Paolo
Ciuchi Sergio
No associations
LandOfFree
Polaron Crossover and Bipolaronic Metal-Insulator Transition in the Holstein model at half-filling does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Polaron Crossover and Bipolaronic Metal-Insulator Transition in the Holstein model at half-filling, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Polaron Crossover and Bipolaronic Metal-Insulator Transition in the Holstein model at half-filling will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-487714