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Condensed Matter papers — page 194

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Bethe ansatz for the one-dimensional small-polaron model with open boundary conditions
The one-dimensional small-polaron model with open boundary conditions is considered in the framework of the quantum inverse scattering method. The spin model which is equivalent to the small-polaron…
Heng Fan, Xi-Wen GuanNov 16, 1997
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Spin diffusion and the spin 1/2 XXZ chain at T=∞ from exact diagonalization
We study the long time behavior of the zz and xx time dependent autocorrelation function of the spin 1/2 XXZ chain at T=∞ by exact diagonalizations on a chain of 16 sites. We find that the…
Klaus Fabricius, Barry M. McCoyNov 15, 1997
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Elastic fields of stationary and moving dislocations in finite samples
Integral expressions are determined for the elastic displacement and stress fields due to stationary or moving dislocation loops in finite samples. These general expressions are valid for anisotropic…
Rodrigo AriasNov 14, 1997
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Quasi-particle excitations and dynamical structure function of trapped Bose-condensates in the WKB approximation
The Bogoliubov equations of the quasi-particle excitations in a weakly interacting trapped Bose-condensate are solved in the WKB approximation in an isotropic harmonic trap, determining the discrete…
András Csordás, Robert Graham, Péter SzépfalusyNov 14, 1997
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On Charged Mesoscopic Metallic Bubbles
We investigate the existence of stable charged metallic bubbles using the shell correction method. We find that for a given mesoscopic system of n atoms of a given metal and q less n (positive)…
Krzysztof Pomorski, Klaus DietrichNov 14, 1997
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Models of stress propagation in granular media
Stress patterns in static granular media exhibit unusual features when compared to either liquids or elastic solids. Qualitatively, we attribute these features to the presence of `stress paths',…
J. -P. Bouchaud, P. Claudin, M. E. Cates et al.Nov 14, 1997
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A Scalar Arching Model
In this paper we propose an extension of the model of Liu, Coppersmith et al., in order to allow for arch formation. This extended model qualitatively captures interesting properties of granular…
P. Claudin, J. -P. BouchaudNov 14, 1997
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Current Density Functional approach to large quantum dots in intense magnetic fields
Within Current Density Functional Theory, we have studied a quantum dot made of 210 electrons confined in a disk geometry. The ground state of this large dot exhibits some features as a function of…
Marti Pi, Manuel Barranco, Agusti Emperador et al.Nov 14, 1997
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Comparison of meanfield and Monte Carlo approaches to dynamic hysteresis in Ising ferromagnets
The dynamical hysteresis is studied in the kinetic Ising model in the presence of a sinusoidal magnetic field both by Monte Carlo simulation and by solving the dynamical meanfield equation for the…
Muktish AcharyyaNov 14, 1997
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Calculation of Spin Tunneling Effects in the Presence of an Applied Magnetic Field
The tunneling splitting of the energy levels of a ferromagnetic particle in the presence of an applied magnetic field - previously derived only for the ground state with the path integral method - is…
J. -Q. Liang, H. J. W. Mueller-Kirsten, A. V. Shurgaia et al.Nov 13, 1997
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A Non-Hermitean Particle in a Disordered World
There has been much recent work on the spectrum of the random non-hermitean Hamiltonian which models the physics of vortex line pinning in superconductors. This note is loosely based on the talk I…
A. ZeeNov 13, 1997
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Low temperature transport in the XXZ model
We present evidence suggesting that spin transport in the gapless phase of the S=1/2 XXZ model is ballistic rather than diffusive. We map the model onto a spinless fermion model whose charge…
B. N. Narozhny, A. J. Millis, N. AndreiNov 12, 1997
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Isotropic Transverse XY Chain with Energy- and Magnetization Currents
The ground-state correlations are investigated for an isotropic transverse XY chain which is constrained to carry either a current of magnetization JM or a current of energy JE. We find that the…
T. Antal, Z. Racz, A. Rakos et al.Nov 12, 1997
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Density of Neutral Solitons in Weakly Disordered Peierls Chains
We study the effects of weak off-diagonal disorder on Peierls systems with a doubly degenerate ground state. We show that for these systems disorder in the electron hopping amplitudes induces a…
M. V. Mostovoy, M. T. Figge, J. KnoesterNov 12, 1997
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Oxygen adsorption on the Ru (10 bar 1 0) surface: Anomalous coverage dependence
Oxygen adsorption onto Ru (10 bar 1 0) results in the formation of two ordered overlayers, i.e. a c(2 times 4)-2O and a (2 times 1)pg-2O phase, which were analyzed by low-energy electron diffraction…
S. Schwegmann, A. P. Seitsonen, V. De Renzi et al.Nov 12, 1997
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Dynamics of Stripes in Doped Antiferromagnets
We study the dynamics of the striped phase, which has previously been suggested to be the ground state of a doped antiferromagnet. Starting from the t-J model, we derive the classical equation…
C. Morais Smith, Y. Dimashko, N. Hasselmann et al.Nov 12, 1997
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Multiphonon decay of strong mode in quantum lattice
A nonperturbative theory of multiphonon anharmonic decay of strongly excited local mode is developed whereby the mode is considered classically and phonons, quantum mechanically. The decay rate of…
Vladimir HizhnyakovNov 11, 1997
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Accurate mapping of quantum Heisenberg magnetic models of spin s on strong-coupling magnon systems
An infinite-U term is introduced into the Holstein-Primakoff-transformed magnon hamiltonian of quantum Heisenberg magnetic models of spin s. This term removes the unphysical spin wave states on…
Bang-Gui Liu, Gerd CzychollNov 11, 1997
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Four-point renormalized coupling constant and Callan-Symanzik beta-function in O(N) models
We investigate some issues concerning the zero-momentum four-point renormalized coupling constant g in the symmetric phase of O(N) models, and the corresponding Callan-Symanzik beta-function. In the…
A. Pelissetto, E. VicariNov 10, 1997
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Transport in a one-dimensional wire connected to leads and proximity effects
We investigate transport through a finite interacting wire connected to noninteracting leads. The conductance of the pure wire is not renormalized by the interactions for any spatial variation of the…
I. Safi, H. J. SchulzNov 10, 1997
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The stability of the O(N) invariant fixed point in three dimensions
We study the stability of the O(N) fixed point in three dimensions under perturbations of the cubic type. We address this problem in the three cases N=2,3,4 by using finite size scaling techniques…
M. Caselle, M. HasenbuschNov 10, 1997
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The `Friction' of Vacuum, and other Fluctuation-Induced Forces
The static Casimir effect describes an attractive force between two conducting plates, due to quantum fluctuations of the electromagnetic (EM) field in the intervening space. Thermal…
Mehran Kardar, Ramin GolestanianNov 7, 1997
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Nonlinear quantum dynamics of strong vibration: relaxation jumps and phonon bursts
We examine quantum decay of localized vibrations in anharmonic crystal lattice. The theory which describes two-phonon anharmonic relaxation can be applied both to local modes associated with…
V. Hizhnyakov, D. NevedrovNov 7, 1997
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Stepwise quantum decay of self-localized solitons
The two-phonon decay of self-localized soliton in a one-dimensional monatomic anharmonic lattice caused by cubic anharmonicity is considered. It is shown that the decay takes place with emission of…
V. Hizhnyakov, D. NevedrovNov 7, 1997
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Anomalous fluctuations of the condensate in interacting Bose gases
We find that the fluctuations of the condensate in a weakly interacting Bose gas confined in a box of volume V follow the law <δN02> V4/3. This anomalous behaviour arises from the…
S. Giorgini, L. P. Pitaevskii, S. StringariNov 7, 1997
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