Related papers: Pairing on Small Clusters in the Peierls-Hubbard M…
We study the electron-phonon coupling in the C60 fullerene within the first-principles GW approach, focusing on the lowest unoccupied t1u three-fold electronic state which is relevant for the superconducting transition in electron doped…
The resonance states embedded in the three-cluster continuum of 6He and 6Be are obtained in the Algebraic Version of the Resonating Group Method. The model accounts for a correct treatment of the Pauli principle. It also provides the…
Effects of short-range correlations on the Coulomb screening, the phonons, and the pairing interactions are examined in electron-phonon systems. First, we derive a model Hamiltonian of Coulomb interactions which includes both the long-range…
Establishing a minimal microscopic model for cuprates is a key step towards the elucidation of a high-$T_c$ mechanism. By a quantitative comparison with a recent \emph{in situ} angle-resolved photoemission spectroscopy measurement in doped…
In this paper we examine the effects of electron-hole asymmetry as a consequence of strong correlations on the electronic Raman scattering in the normal state of copper oxide high temperature superconductors. Using determinant quantum Monte…
A full coupled-cluster expansion suitable for sparse algebraic operations is developed by expanding the commutators of the Baker-Campbell-Hausdorff series explicitly for cluster operators in binary representations. A full coupled-cluster…
The pi electrons of isolated fullerene anions C60^{n-} (n betwen 1 and 6) are a quite unique finite system of electrons with an attractive interaction due to exchange of intramolecular phonons. This interaction may overwhelm Hund's rule and…
The Hubbard model extended by either nearest-neighbour Coulomb correlation and/or nearest neighbour Heisenberg exchange is solved analytically for a triangle and tetrahedron. All eigenvalues and eigenvectors are given as functions of the…
A simple, yet accurate solution of the electron-phonon coupling problem in C_{60} is presented. The basic idea behind it is to be found in the parametrization of the ground state electronic density of the system calculated making use of…
We investigate the influence of electron-phonon coupling on the superexchange interaction of magnetic insulators. Both the Holstein-Hubbard model where the phonons couple to the electron density, as well as an extended Su, Schrieffer,…
We report detailed results on ionization in metallic quantum--dot (QD) nanorings described by the extended Hubbard model at half filling obtained by exact numerical diagonalization. In spite of very strong electron correlations, the…
The Klein paradox describes an incoming electron being scattered at a supercritical barrier to create electron-positron pairs, a phenomenon widely discussed in textbooks. While demonstrating this phenomenon experimentally with the…
We study the Cu_{5}O_{4} cluster by exact diagonalization of a three-band Hubbard model and show that bound electron or hole pairs are obtained at appropriate fillings, and produce superconducting flux quantisation. The results extend…
We re-examine the Peierls insulator to Mott insulator transition scenario in the one-dimensional Holstein-Hubbard model where, at half-filling, electron-phonon and electron-electron interactions compete for establishing charge- and…
We perform time-resolved exact diagonalization of the Hubbard model with time dependent hoppings on small clusters of up to $12$ sites. Here, the time dependence originates from a classic electromagnetic pulse, which mimics the impact of a…
We investigate the Peierls transition in the one-dimensional Peierls-Hubbard model at half filling in the adiabatic approximation for the lattice. Depending on the value of the electron-lattice coupling constant g the equilibrium…
Previous studies have shown that bipartite Hubbard systems with inhomogeneous hopping amplitudes can exhibit higher pair-binding energies than the uniform model. Here we examine whether this result holds for systems with a more generic band…
We discuss the properties of few electrons and electron-hole pairs confined in coupled semiconductor quantum dots, with emphasis on correlation effects and the role of tunneling. We shall discuss, in particular, exact diagonalization…
We describe quantum entanglement inherent to the polaron ground states of coupled electron-phonon (or, more generally, particle-phonon) systems based on a model comprising both local (Holstein-type) and nonlocal (Peierls-type) coupling. We…
Exact thermal studies of small (4-site, 5-site and 8-site) Hubbard clusters with local electron repulsion yield intriguing insight into phase separation, charge-spin separation, pseudogaps, condensation, in particular, pairing fluctuations…