相关论文: Mass enhancement in narrow band systems
The behavior of the 1D Holstein polaron is described, with emphasis on lattice coarsening effects, by distinguishing between adiabatic and nonadiabatic contributions to the local correlations and dispersion properties. The original and…
We use both a perturbative Green's function analysis and standard perturbative quantum mechanics to calculate the decrease in energy and the effective mass for an electron interacting with acoustic phonons. The interaction is between the…
We present selected results for the Holstein molecular crystal model in one space dimension as determined by the Global-Local variational method, including complete polaron energy bands, ground state energies, and effective masses. We…
We consider an electron-phonon system in two and three dimensions on square, hexagonal and cubic lattices. The model is a modification of the standard Holstein model where the optical branch is appropriately curved in order to have a…
The single-polaron band structure of the Holstein model in one and two dimensions is studied using a new form of resummed strong-coupling perturbation theory. Well converged results are obtained for phonon frequencies of the order of the…
The Holstein Hubbard and Holstein t--J models are studied for a wide range of phonon frequencies, electron--electron and electron--phonon interaction strengths on finite lattices with up to ten sites by means of direct Lanczos…
We present the first numerically exact study of a polaron with quadratic coupling to the oscillator displacement, using two alternative methodological developments. Our results cover both anti-adiabatic and adiabatic regimes and the entire…
An exact diagonalization technique is used to investigate the low-lying excited polaron states in the Holstein model for the infinite one-dimensional lattice. For moderate values of the adiabatic ratio, a new and comprehensive picture,…
The nonadiabatic electron-phonon corrections for the superconducting pairing are investigated for a specific tight-binding model corresponding to a 2d square lattice. This permits to investigate the role of various specific properties like…
Ground-state and dynamical properties of the 2D Holstein t-J model are examined by means of direct Lanczos diagonalization, using a truncation method of the phononic Hilbert space. The single-hole spectral function shows the formation of a…
We obtain analytical expressions for the large- and small-radius polarons on the one-dimensional lattice in the TBA approximation. The equations of motion for this model are treated classically for the oscillator subsystem, while a quantum…
We study bipolaron formation and bipolaronic superconductivity on a square lattice, where electrons couple to both local Holstein phonons via on-site charge density and nonlocal bond Su-Schrieffer-Heeger phonons via modulation of hopping…
The application of optical lattices allows a tuning of the geometry of Bose-Einstein condensates to effectively reduced dimensions. In the context of solid state physics the consideration of the low-dimensional Fr\"ohlich polaron results in…
The polaron binding energy and effective mass in a degenerate polar gas is calculated in the fractional-dimensional approach under plasmon pole approximation.The effect of carrier densities on the static and dynamic screening correction of…
We present a small polaron picture and show that finite bandwidth effects are important to understand colossal magnetoresistance. Besides the polaron size parameter, we show that there is another parameter (adiabaticity parameter) that is…
Recent experiments on metallic nanohybrids have revealed unusually strong electron-phonon effects emerging from nanoscale interfaces, despite the weak coupling character of the constituent bulk materials. Motivated by these observations, we…
We investigate the interplay of electron-phonon (EP) coupling and strong electronic correlations in the frame of the two-dimensional (2D) Holstein t-J model (HtJM), focusing on polaronic ordering phenomena for the quarter-filled band case.…
We provide a comprehensive solution to the lattice dynamics problem in the two dimensional Holstein model at finite electron density and finite temperature. We work in the physically relevant adiabatic regime and vary the electron-phonon…
The hopping of an electron, interacting with many ions of a lattice via the long-range (Fr\"{o}hlich) electron-phonon interaction and optical absorption are studied at zero temperature. Ions are assumed to be isotropic three-dimensional…
The Hubbard model, which augments independent-electron band theory with a single parameter to describe electron-electron correlations, is widely regarded to be the `standard model' of condensed matter physics. The model has been remarkably…