Related papers: Off-diagonal Interactions, Hund's Rules and Pair-b…
It is shown that, an entire class of off-diagonally disordered linear lattices composed of two basic building blocks and described within a tight binding model can be tailored to generate absolutely continuous energy bands. It can be…
The effective on-site Coulomb interaction (Hubbard $U$) between localized electrons at crystal surfaces is expected to be enhanced due to the reduced coordination number and reduced subsequent screening. By means of first principles…
Electron pairing in one-dimensional binary Hubbard chains is studied for different values of the band-filling using the Density Matrix Renormalization Group method. The systems consist of linear arrays of sites with two types of on-site…
Density-matrix renormalization group is used to study the pairing when both of electron-electron and electron-phonon interactions are strong in the Holstein-Hubbard model at half-filling in a region intermediate between the adiabatic…
In order to numerically study electron correlation effects in multi-orbital systems, we propose a new type of discrete transformation for the exchange (Hund's coupling) and pair-hopping interactions to be used in the dynamical mean field…
Comparing experimental data for high temperature cuprate superconductors with numerical results for electronic models, it is becoming apparent that a hopping along the plaquette diagonals has to be included to obtain a quantitative…
We consider the orbitally degenerate 3-band Hubbard model with on-site interactions which favor low spin and low orbital angular momentum using standard second order perturbation theory in the large Hubbard-U limit. At even integer filling…
We study the effects of bond-charge interaction (or correlated hopping) on the properties of the extended ({\it i.e.,} with both on-site ($U$) and nearest-neighbor ($V$) repulsions) Hubbard model in one dimension at half-filling. Energy…
In the standard mean-field treatment of superconductors, the electron-electron interactions are assumed to be written in terms of local density operators. However, more general interactions, such as pair-hopping interactions, may exist or…
To date, the Hubbard model and its strong coupling limit, the t-J model, serve as the canonical model for strongly correlated electron systems in solids. Approximating the Coulomb interaction by only the on-site term (Hubbard U-term),…
We investigate, by numerically calculating the charge stiffness, the effects of random diagonal disorder and electron-electron interaction on the nature of the ground state in the 2D Hubbard model through the finite size exact…
A derivation of the t-J model of a highly-correlated solid is given starting from the general many-electron Hamiltonian with account of the non-orthogonality of atomic wave functions. Asymmetry of the Hubbard subbands (i.e. of ``electron''…
We investigate the influence of electron-electron interactions on the conductance of two-dimensional disordered spinless electrons. By using an efficient numerical method which is based on exact diagonalization in a truncated basis of…
We study theoretically the effects of short-range electron-electron interactions on the electronic structure of graphene, in the presence of single substitutional impurities. Our computational approach is based on the $\pi$ orbital…
In condensed matter systems with the Coulomb interaction playing an important role one expects, besides the on-site (local) Hubbard-type interaction, that also other (non-local) terms depending on the site occupancy, known as correlated or…
The Hubbard and related models serve as a fundamental starting point in understanding the novel experimental phenomena in correlated electron materials, such as superconductivity, Mott insulator, magnetism and stripe phases. Recent…
The electron-hole states of semiconductor quantum dots are investigated within the framework of empirical tight-binding descriptions for Si, as an example of an indirect gap material, and InAs and CdSe as examples of typical III-V and II-VI…
The long-range correlation energies and the off-diagonal interactions are studied and a general formula for correlation energy $E_c$ of the $\pi$ electron systems is given, which is beyond the nearest-neighbor electron-electron interactions…
The screened electron-electron interaction in a multi-band electron system is calculated within the random phase approximation and in the tight-binding representation. The obtained dielectric matrix contains, beside the usual site-site…
We study the combined impact of random disorder and electron-electron, and electron-hole interactions on the absorption spectra of a three-dimensional Hubbard Hamiltonian. We determine the single-particle Green's function within the typical…