Related papers: Single bipolaronic Transition in Jahn-Teller Model
We consider a one dimensional model of an electron in a doubly (or nearly) degenerate band that interacts with elastic distortions. We show that the electron equations of motion reduce to a set of coupled non-linear Schrodinger equations.…
Phonon-mediated superconductivity is conventionally thought to be capped at a transition temperature $T_{\mathrm{c}}$ no larger than roughly one-tenth of the phonon frequency $\Omega$, a bound rooted in the breakdown of Migdal-Eliashberg…
A two-site double exchange model with a single polaron is studied using a perturbation expansion based on the modified Lang-Firsov transformation. The antiferromagnetic to ferromagnetic transition and the crossover from small to large…
When an electron interacts with phonons, the electron can exhibit either free electron-like or polaron-like properties. The latter tends to occur for very strong coupling, and results in a phonon cloud accompanying the electron as it moves,…
We study electron propagation in a molecular lattice model. Each molecular site involves doubly degenerate electronic states coupled to doubly degenerate molecular vibration, leading to a so--called E-e type of Jahn-Teller Hamiltonian. For…
We investigate the Holstein model by using the dynamical mean-field theory combined with the exact diagonalization method. Below a critical temperature Tcr, a coexistence of the polaronic and the bipolaronic solutions is found for the same…
We investigate the interaction of strongly correlated electrons with phonons in the frame of the Hubbard-Holstein model. The electron-phonon interaction is considered to be strong and is an important parameter of the model besides the…
We study the interplay between electron-electron interaction and a Jahn-Teller phonon coupling in a two-orbital Hubbard model. We demonstrate that the e-ph interaction coexists with the Mott localization driven by the Hubbard repulsion U,…
We study an interplay between the orbital degeneracy and spin-orbit coupling giving rise to spin-orbital entangled states. As a specific example, we analyze the interaction of electrons occupying triply degenerate single-ion $t_{2g}$ levels…
We consider a polaron model where molecular \emph{rotations} are important. Here, the usual hopping between neighboring sites is affected directly by the electron-phonon interaction via a {\em twist-dependent} hopping amplitude. This model…
We analyze the transition temperature $T_c$ of bipolaronic superconductivity in a bond Su-Schrieffer-Heeger (bond-SSH) model -- also known as a bond Peierls model -- where the electron hoppings are modulated by bond phonons. Using a…
The single bipolaron problem is examined in the context of the 1D Holstein-Hubbard model, emphasizing analogies and differences with respect to the complementary single polaron physics. The bipolaron band structure below the phonon…
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…
It is widely accepted that phonon-mediated high-temperature superconductivity is impossible at ambient pressure, because of the very large effective masses of polarons/bipolarons at strong electron-phonon coupling. Here we challenge this…
We use continuous-time quantum Monte Carlo simulations to study retardation effects in the metallic, quarter-filled Holstein model in one dimension. Based on results which include the one- and two-particle spectral functions as well as the…
We investigate the Mott transitions in two-band Hubbard models with different bandwidths. Applying dynamical mean field theory, we discuss the stability of itinerant quasi-particle states in each band. We demonstrate that separate Mott…
We present a theoretical study of a possibility of superconductivity in a three dimensional molecular conductor in which the interaction between electrons in doubly degenerate molecular orbitals and an {\em intra}molecular vibration mode is…
The possibility of "orbitally selective Mott transitions" within a multiband Hubbard model, in which one orbital with large on-site electron-electron repulsion $U_1$ is insulating and another orbital, to which it is hybridized, with small…
The formation of a finite density multipolaronic state is analyzed in the context of the Holstein model using the Dynamical Mean-Field Theory. The spinless and spinful fermion cases are compared to disentangle the polaron crossover from the…
We analyze the ground-state properties of strongly-correlated electrons coupled with phonons by means of a generalized Gutzwiller wavefunction which includes phononic degrees of freedom. We study in detail the paramagnetic half-filled…