Hamiltonian Hubbard

Orientational disorder and packing irregularities in terms of a modified Anderson-Hubbard Hamiltonian [63,64] will lead to a distribution of the on-site Coulomb interaction as well as of the interaction of electrons on different (at least neighboring) sites as it was explicitly pointed out by Cuevas et al. [65]. Compared to the Coulomb-gap model of Efros and Sklovskii [66], they took into account three different states of charge of the mesoscopic particles, i.e. neutral, positively and negatively charged. The VRH behavior, which dominates the electrical properties at low temperatures, can conclusively be explained with this model. 

Using these parameters, the electronic state of molecular conductors is described with the Hubbard-Hamiltonian... 

The competition between these two terms produces a large variety of electronic structures in molecular systems. The condition l U favors itinerant metallic states, whereas the condition t stabilizes localized insulating states. In the latter case, the Hubbard Hamiltonian is reduced to the Heisenberg Hamiltonian... 

This discussion is also applicable to the %-d interacting system with slight modification. The Hubbard Hamiltonian for a pair of re-electron donor and (i-electron magnetic anion is expressed as... 

If the basis set is restricted to one pn basis function on each sp2 carbon, if the two-electron integrals ignore all three-center or four-center ones, and if we exclude exchange components, one has the Pariser-Parr-Pople model. If, further, all two-electron integrals are set to zero except for the repulsion between opposite spins on the same site and the one-electron tunneling terms are restricted to nearest neighbors, the result is the Hubbard Hamiltonian... 

We consider an array of quantum dots modeled by the one-dimensional Hubbard Hamiltonian of the form [82]... 

Hence this enlarged Hubbard Hamiltonian can be written as... 

Now we generalize this density matrix formalism [19,20] for the degenerate Hubbard Hamiltonian which, with usual notations, reads ... 

We adopt an extended Hubbard Hamiltonian postulated for the active space of the form... 

In the case of delocalized basis states tpa(r), the main matrix elements are those with 0 = 7 and f3 = 6, because the wave functions of two different states with the same spin are orthogonal in real space and their contribution is small. It is also true for the systems with localized wave functions tpa(r), when the overlap between two different states is weak. In these cases it is enough to replace the interacting part by the Anderson-Hubbard Hamiltonian, describing only density-density interaction... 

The Coulomb interaction inside a system is described by the Anderson-Hubbard Hamiltonian... 

Hubbard Hamiltonian An effective Hamiltonian, which includes on-site electron-electron repulsion and a resonance integral, and is used in VB to calculate states of molecular species with an average of one electron per site (atom), e.g., of polymers. 

One of the simplest models describing a system of strongly correlated electrons on a crystal lattice is the Hubbard Hamiltonian [8] ... 

Making use of this treatment for all electrons and sites, one obtains that the Hubbard Hamiltonian with infinite repulsion can be written in the form... 

One of the simplest zr-electron models of a conjugated polymer with a macroscopic ground state spin is a polyallyl chain (Fig.2) described by the Hubbard Hamiltonian [20] ... 

One of the simple models of high-Tc superconducting copper oxides is a two-band Hubbard Hamiltonian (so called Emery model) [46]... 

To describe the electronic structure of carbon nanotubes the Hubbard model has been chosen as it can describe the electrical and magnetic properties and high temperature superconductivity effects also [11]. The model includes the terms of the electron jump energy in vicinity approach and the energy of Coulomb s repulsion of two electrons localized on the same point of unit cell. Hubbard Hamiltonian for the described system is following [11] ... 

What is a minimum model for describing the main physics of a single Q1O2-plane In this paper we employ an effective one-band Hubbard Hamiltonian ... 

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