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	Andreas Mielke: Areas of research
		A class of models where we were able to proof the existence and the uniqueness of ferromagnetic ground states are the so called flat-band systems.
		It is well known that the Hubbard model on a line graph has a flat band and ferromagnetic ground states in a certain density range.
		We show that for a Hubbard model on a line graph of a planar bipartite graph the ferromagnetic ground state is stable if one adds a special contribution to the kinetic energy which lifts the degeneracy of the lowest single particle state.
	www.tphys.uni-heidelberg.de /~mielke/hubbard.en.html (1023 words)

	Strongly Correlated Electrons and Unconventional Superconductivity (Site not responding. Last check: 2007-10-21)
		In the limit of strong correlations the ground state of the Hubbard model for a concentration of 1 electron/ lattice site (the so-called half-filled band) is an antiferromagnetic insulator, and this is in agreement with the HTS phenomenology.
		Namely, we have studied the t-t' Hubbard model in the limit of intermediate correlations and/or for electron fillings less than 0.7, when the standard apparatus of many body theory based on various versions of perturbation theory may be applied.
		Within the T-matrix approximation we have later constructed a magnetic phase diagram of the t-t' Hubbard model in the low density limit and we have shown that the ferromagnetic phase is stable in a finite region of the phase diagram [5].
	www.fmph.uniba.sk /~kftl/research/51.html (920 words)

	Jim Hague : Hubbard model (Site not responding. Last check: 2007-10-21)
		Hubbard's model [Hubbard, 1963] is designed to represent interactions between electrons in tight binding systems.
		The derivation of the Hamiltonian for the Hubbard model is found in his original paper (this Hamiltonian was simultaneously derived by Gutzwiller and Kanamori).
		At half filling, the strong coupling limit of the Hubbard model coincides with second-order perturbation theory, which was used under the name of iterated perturbation theory [Georges, 1992] (IPT) to obtain spectral functions and physical quantities for this model.
	www.physics.uc.edu /~jph/research/hubbard (322 words)

	The behaviour of the Hubbard model in the presence of a small hole concentration in limit (P. Gurin and Zs. ... (Site not responding. Last check: 2007-10-21)
		The behaviour of the Hubbard model in the presence of a small hole concentration in limit (P. Gurin and Zs.
		The behaviour of the Hubbard model in the presence of a small hole concentration in
		Nagaoka's theorem states that the fully polarized ferromagnetic state is the unique ground state of the infinitely repulsive Hubbard model with precisesly one hole.
	dtp.atomki.hu /HOME-PAGE/prog99/node65.html (280 words)

	The One-Dimensional Hubbard Model - Cambridge University Press
		An important example is the Hubbard model, which describes interacting electrons in narrow energy bands, and which has been applied to problems as diverse as high-Tc superconductivity, band magnetism, and the metal-insulator transition.
		The algebraic approach to the Hubbard model; 13.
		The Yangian symmetry of the Hubbard model; 15.
	www.cambridge.org /uk/catalogue/catalogue.asp?isbn=0521802628 (238 words)

	Citebase - On Chemical Potential of a Generalized Hubbard Model with Correlated Hopping at Half-Filling (Site not responding. Last check: 2007-10-21)
		In the present paper we study chemical potential of a generalized Hubbard model with correlated hopping at half-filling using a generalized mean-field approximation.
		Chemical potential of generelized Hubbard model with correlated hoppig as function of hopping integrals at zero temperature is found.
		The dependences of chemical potential of a generalized Hubbard model with correlated hopping on the model parameters are different in metallic and insulating phases leading to a kink at the point of metal-insulator transition in the ground state.
	citebase.eprints.org /cgi-bin/citations?archiveID=oai:arXiv.org:cond-mat/9910068 (392 words)

	Thermodynamics of the strongly correlated Hubbard model
		High-temperature expansions for the specific heat and susceptibility of the strongly correlated Hubbard model are compared with corresponding quantities for spinless free fermions and free spins.
		It is found numerically that, when the temperature is high, the ratio of the specific heat of the strongly correlated Hubbard model to that of spinless free fermions approaches a particle-density-dependent constant.
		For fixed temperature, the susceptibility of the Hubbard model is less (greater) than that of free spins when the particle density is below (above) a certain threshold density of approximately 0.7.
	stacks.iop.org /0305-4470/24/L279 (274 words)

	Armen N KOCHARIAN
		A.N. Kocharian, C. Yang and Y.L. Chiang - "The phase diagram and inhomogeneous superconductivity in the one-dimensional attractive Hubbard model", Physica C 341-348, pp.
		A.N. Kocharian, A.K. Jermakian and A.S. Saakian - "Finite-size clusters in discrete Hubbard model with transverse and longitudinal magnetic fields", Physica B 259-261, pp.
		A.N. Kocharian, A.K. Jermakian and C.Yang - "Off-diagonal superconducting correlations and Nagaoka instability in repulsive Hubbard model", Physica B 230-232, pp.
	www.csun.edu /~akocha/List.htm (3026 words)

	Session J11 - HTSC Theory V: General Theory II.
		From diagramatic studies of the two-dimensional Hubbard model, it is obtained that the imaginary part of the self-energy is proportional to \epsilon^2\log\epsilon, and the Fermi-liquid picture is considered to be valid.
		We show that our model is generic and is capable of reproducing the non-trivial details of the low energy LDA band structure, in particularly those arising from the dimpling of the CuO planes and variation of the apical oxygen distance to plane Cu.
		The pairing instability in the Hubbard and the extended Hubbard models for a 2D lattice is examined by using the perturbation diagram approach.
	flux.aps.org /meetings/YR97/BAPSMAR97/abs/S2410.html (2080 words)

	Dynamic Hubbard model - numerical study (Site not responding. Last check: 2007-10-21)
		A one-dimensional model of electrons locally coupled to spin-1/2 degrees of freedom is studied by numerical techniques.
		The model is one in the class of $dynamic$ $Hubbard$ $models$ that describe the relaxation of an atomic orbital upon double electron occupancy due to electron-electron interactions.
		The qualitative physics of this model and others in its class, obtained through approximate analytic calculations, is that superconductivity occurs through hole undressing even in parameter regimes where the effective on-site interaction is strongly repulsive.
	physics.ucsd.edu /~jorge/abstracts/qmc.html (162 words)

	The One-Dimensional Hubbard Model (Site not responding. Last check: 2007-10-21)
		The description of solids at a microscopic level is complex, involving the interaction of a huge number of its constituents, such as ions or electrons.
		An important example is the Hubbard model, which describes interacting electrons in narrow energy bands, and which has been applied to problems as diverse as high-Tc superconductivity, band magnetism, and the metal-insulator transition.
		Many methods devised to analyse such effects have been applied to this model, both to provide complementary insights into what is known from the exact solution, and as an ultimate test of their quality.
	www.itp.uni-hannover.de /~frahm/TheBook.html (237 words)

	Rapport annuel 95-96
		This model is an extension of the usual Hubbard model, to which we have added a next-nearest neighbor hopping term t
		Through the direct determination of the ground state properties of the finite lattice RDA Hamiltonian using numerical exact diagonalization, we directly calculate the critical properties of the zero temperature metal-insulator transition in the half-filled infinite dimensional Hubbard model, a subject of recent controversy.
		In the framework of the thesis of F. Naef, we undertook a systematic study of the dynamic spin and energy correlations in the one-dimensional spin 1/2 Heisenberg model.
	www.unifr.ch /physics/tss (2045 words)

	Photography by Bob Hubbard - Model Search
		My goal, is to shoot great pictures in a relaxed and comfortable manner, to capture a memory, a dream, or a bit of fantasy, and work within your comfort zones that we can both be proud of what we create.
		I am happy to do test shoots with aspiring models as my time permits, and will often consider time-trades if you have a look I can use in one of the numerous projects I have ongoing.
		Payment is available in a variety of forms, but please remember, unlike the corporate world, art shoots (which much of my personal work tends to be) rarely have paying sponsors.
	bobhubbardphotography.com /modelsearch.htm (638 words)

	Citebase - Strong coupling phases of the $t-t'$ Hubbard model (Site not responding. Last check: 2007-10-21)
		We study the strong coupling regime of the $t-t'$ Hubbard model,filled up to the level of the van Hove singularities, by means of an exact diagonalization approach.
		We apply a renormalization group approach to the determination of the phase diagram of the t-t' Hubbard model at the Van Hove filling, as function of t'/t, for small values of U/t.
		Quantum Monte Carlo is used to investigate the possibility of d_{x^2-y^2} superconductivity in the two-dimensional repulsive Hubbard model.
	citebase.eprints.org /cgi-bin/citations?archiveID=oai:arXiv.org:cond-mat/9609162 (1079 words)

	Negative-U extended Hubbard model for doped barium bismuthatesePrints@IISc - Open Access Archive of IISc Research ... (Site not responding. Last check: 2007-10-21)
		We present detailed mean-field and random-phase-approximation studies of the negative-U, extended Hubbard model with a view to understanding the properties of the doped barium bismuthates.
		In particular, we obtain the phase diagram, the excitation spectrum, and the optical conductivity in the semiconducting phase of the bismuthates.
		We show by explicit calculations how this model leads to a natural explanation for the two, well-separated transport and optical gaps observed in the semiconducting phases of the bismuthates.
	eprints.iisc.ernet.in /archive/00001166 (214 words)

	Two-site Hubbard model, the Bardeen-Cooper-Schrieffer model, and the concept of correlation entropy. (Site not responding. Last check: 2007-10-21)
		Two-site Hubbard model, the Bardeen-Cooper-Schrieffer model, and the concept of correlation entropy.
		Exactly solvable models (the two-electron two-site Hubbard model and the Bardeen-Cooper-Schrieffer model) are revisited in terms of their natural occupation numbers (eigenvalues of the true, i.e., correlated, one-particle density matrix).
		Entropylike expressions that may serve as measures of the correlation strength are related to possible reference states for the definition of correlation and discussed as functions of the system parameters.
	www.mpi-stuttgart.mpg.de /andersen/docs/pub/abstract/and1997-29.html (115 words)

	The Mott-Anderson transition in the disordered one-dimensional Hubbard model (Site not responding. Last check: 2007-10-21)
		The Mott-Anderson transition in the disordered one-dimensional Hubbard model
		We use the density matrix renormalization group to study the quantum transitions that occur in the half-filled one-dimensional fermionic Hubbard model with onsite potential disorder.
		We also establish the finite-size corrections to the charge gap and the spin-spin correlation length in the presence of disorder and using a finite-size-scaling analysis we obtain the zero temperature phase diagram of the various quantum phase transitions that occur in the disorder-interaction plane.
	archiv.tu-chemnitz.de /pub/1998/0140 (131 words)

	DIRT LATE MODEL SUPERSITE - LATEMODELRACER.COM
		McCool scores O'Reilly SUPR Late Model victory at Pike County Speedway
		Parker Jr captures SWDRA Late Model victory at Prescott Valley Speedway
		Blair wins Crate Late Models at inaugural Central PA Speedway Nationals
	www.latemodelracer.com (960 words)

	Asgard: Project Description
		The underlying goal of this project is to characterize the breakdown of the Landau-Fermi liquid in a two-dimensional system of repulsively interacting electrons on a lattice as a function of interaction strength and particle density.
		Such phases are theoretically well understood in quasi-one-dimensional models and exhibit many salient properties making them a candidate for the description of the so-called spin-gap or pseudo-gap state of the underdoped high-T
		To analyze this question we study the Wilsonian renormalization group (RG) flow of the interactions in the two-dimensional t-t' Hubbard model in a N-patch representation of the whole Fermi surface (FS).
	www.asgard.ethz.ch /day/ws0001/chonerka.phtml (635 words)

	Publication List
		Srtongly Correlated Fermions in the t-J and t-J-J' models
		Flux Quantization in the two-Dimensional Repulsive and Attractive Hubbard models.
		Temperature Derivative of the Superfluid Density in the Attractive Hubbard Model.
	theorie.physik.uni-wuerzburg.de /~assaad/pub.html (876 words)

	[No title]
		[35] P.J.H. Denteneer, ``Strong-coupling expansion for the Hubbard model in arbitrary dimension using slave bosons'', Phys.
		[27] P.J.H. Denteneer, ``Superfluid density in the two-dimensional attractive Hubbard model: Quantitative estimates'', Phys.
		[24] P.J.H. Denteneer, Guozhong An, and J.M.J. van Leeuwen, ``The helicity modulus in the two-dimensional Hubbard model'', Phys.
	www.lorentz.leidenuniv.nl /~pjhdent/publist.txt (1517 words)

	Exact Results Related to the Extended Hubbard Model Obtained by the Optimal Ground State Method. (Zs. Szabó) (Site not responding. Last check: 2007-10-21)
		However, in recent years a few exact, non-perturbative methods have also been developed, by means of which the ground state of Hubbard and Hubbard-like models can be investigated in large parameter regimes [1, 2].
		On the line of the optimal ground-state method[2] there are basically two different ways to enlarge the region of guaranteed stability for a given ground state, namely the choice of a larger local Hamiltonian or the incorporation of next-nearest neighbor interactions.
		and for the fully saturated ferromagnetic state in the parameter space of an extended Hubbard model with a half-filled band in the thermodynamic limit.
	dtp.atomki.hu /HOME-PAGE/prog98/node71.html (280 words)

	Hubbard model - Wikipedia, the free encyclopedia
		Please help recruit one, or improve this page yourself if you can.
		The Hubbard Model is a commonly used approximation for the behavior of electrons on a lattice (e.g.
		The 1-dimensional Hubbard Hamiltonian is H = T + U where the hopping term is
	en.wikipedia.org /wiki/Hubbard_model (132 words)

	Dynamic Hubbard Model (Site not responding. Last check: 2007-10-21)
		Dynamic Hubbard models describe coupling of a boson degree of freedom to the on-site electronic double occupancy.
		In the limit of infinite boson frequency this coupling gives rise to a correlated hopping term in the effective Hamiltonian and to superconductivity when the Fermi level is near the top of the band.
		It is found that finite frequency enhances the tendency to superconductivity in this model.
	physics.ucsd.edu /~jorge/abstracts/dynw.html (100 words)

	[No title] (Site not responding. Last check: 2007-10-21)
		Density-functional study of the Mott gap in the Hubbard model
		We study the Mott insulating phase of the one-dimensional Hubbard model using a local-density approximation (LDA) that is based on the Bethe Ansatz (BA).
		We find that in one-dimensional quantum systems the contribution of the discontinuity to the full gap is more important than that of the band-structure gap, and discuss some consequences this finding has for electronic-structure calculations.
	www.if.sc.usp.br /~capelle/mott.html (117 words)

	3-band Hubbard model in infinite dimensions. (Site not responding. Last check: 2007-10-21)
		The 3-band Hubbard model is used to describe electronic correlations on the copper - and oxygen -orbitals of the quasi two-dimesional -planes of the HTSC.
		As a consequence, lattice models can be mapped onto effective impurity models, embedded in a self-consistently determined effective medium.
		Interesting results were found including the particle-hole asymmetry of the magnetic phase diagram originating in the oxygen degrees of freedom as seen in experiments on HTSC.
	www.physics.uc.edu /~tmaier/resume1/node14.html (172 words)

	The 1D Hubbard model
		A study of the 1D Hubbard model by means of the
		The Bethe Ansatz technique does not provide a complete framework to study the 1D Hubbard model since it does allow the evaluation of the response functions only in some limiting cases.
		These results show that the method is a reasonable framework to study the one-dimensional Hubbard model.
	scs.sa.infn.it /research/activity/node2.html (451 words)

	More about IRRMA (Site not responding. Last check: 2007-10-21)
		Orbital magnetic susceptibility of the attractive Hubbard model
		Our analysis of the orbital magnetic susceptibility chi of the attractive Hubbard model, above the superconducting transition temperature T/sub c/, is based on the usual T-matrix approximation to the electronic self-energy.
		In this framework the one-electron Green's function is coupled to virtual pair fluctuations.
	irrmalin1.epfl.ch /PUBLICATIONS/ABSTRACTS/1999/art9.html (73 words)

	Dynamic Hubbard Model (Site not responding. Last check: 2007-10-21)
		The Hubbard on-site repulsion $U$ between opposite spin electrons on the same atomic orbital is widely regarded to be the most important source of electronic correlation in solids.
		Here we extend the Hubbard model to account for the fact that the experimentally measured atomic $U$ is different from the one obtained by calculation of the atomic Coulomb integral.
		The resulting model describes quasiparticles that become increasingly dressed as the number of electrons in the band increases.
	physics.ucsd.edu /~jorge/abstracts/dynhub.html (117 words)

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