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Condensed Matter papers — page 72

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Diffusion on random site percolation clusters. Theory and NMR microscopy experiments with model objects
Quasi two-dimensional random site percolation model objects were fabricate based on computer generated templates. Samples consisting of two compartments, a reservoir of H2O gel attached to a…
Andreas Klemm, Ralf Metzler, Rainer KimmichDec 6, 2001
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Common features of nanoscale structural correlations in magnetoresistive manganites with ferromagnetic low-temperature state
We report x-ray scattering studies of nanoscale structural correlations in Nd1-xSrxMnO3 and La1-x(Ca,Sr)xMnO3, x=0.2--0.5. We find that the correlated regions possess a…
V. Kiryukhin, T. Y. Koo, A. Borissov et al.Dec 5, 2001
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Interaction of a Kink-Soliton with a Breather in a Fermi-Pasta-Ulam Chain
Collision process between breather and moving kink-soliton is investigated both analytically and numerically in Fermi-Pasta-Ulam (FPU) chains. As it is shown by both analytical and numerical…
Ramaz KhomerikiDec 5, 2001
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Implementation of the Hierarchical Reference Theory for simple one-component fluids
Combining renormalization group theoretical ideas with the integral equation approach to fluid structure and thermodynamics, the Hierarchical Reference Theory is known to be successful even in the…
Albert Reiner, Gerhard KahlDec 3, 2001
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Kinetic energy density functionals for non-periodic systems
Kinetic energy functionals of the electronic density are used to model large systems in the context of density functional theory, without the need to obtain electronic wavefunctions. We discuss the…
Nicholas Choly, Efthimios KaxirasDec 3, 2001
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The effect of non-ideal market conditions on option pricing
Option pricing is mainly based on ideal market conditions which are well represented by the Geometric Brownian Motion (GBM) as market model. We study the effect of non-ideal market conditions on the…
Josep Perello, Jaume MasoliverDec 3, 2001
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Selected aspects of physics of fermionic bubbles
We discuss properties of the Fermi system which contain one or more spherical (or almost spherical) objects. The interplay between various effects, such as shell correction and chaotic behavior is…
Piotr Magierski, Aurel BulgacDec 3, 2001
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Entropic effects on the structure of Lennard-Jones clusters
We examine in detail the causes of the structural transitions that occur for those small Lennard-Jones clusters that have a non-icosahedral global minima. Based on the principles learned from these…
Jonathan P. K. Doye, Florent CalvoDec 2, 2001
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Er2Ti2O7: Evidence of Order by Disorder in a Frustrated Antiferromagnet
Er2Ti2O7 has been suggested to be a realization of the frustrated < 111 > XY pyrochlore lattice antiferromagnet, for which theory predicts fluctuation-induced symmetry breaking in a highly…
J. D. M. Champion, M. J. Harris, P. C. W. Holdsworth et al.Dec 1, 2001
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Quantum spin chains with regularly alternating bonds and fields
We consider the spin-1/2 XY chain in a transverse field with regularly varying exchange interactions and on-site fields. In two limiting cases of the isotropic XX and extremely anisotropic (Ising)…
Oleg DerzhkoDec 1, 2001
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Three-dimensional gonihedric spin system
We perform Monte Carlo simulations of a three-dimensional spin system with a Hamiltonian which contains only four-spin interaction term. This system describes random surfaces with extrinsic curvature…
G. Koutsoumbas, G. K. SavvidyNov 30, 2001
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Electron Paramagnetic Resonance Linewidths and Lineshapes for the Molecular Magnets Fe8 and Mn12
We study theoretically Electron Paramagentic Resonance (EPR) linewidths for single crystals of the molecular magnets Fe8 and Mn12 as functions of energy eigenstates Ms, frequency, and…
Kyungwha Park, M. A. Novotny, N. S. Dalal et al.Nov 30, 2001
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The dynamics of a strongly driven two component Bose-Einstein Condensate
We consider a two component Bose-Einstein condensate in two spatially localized modes of a double well potential, with periodic modulation of the tunnel coupling between the two modes. We treat the…
G. L. Salmond, C. A. Holmes, G. J. MilburnNov 30, 2001
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Symmetry Properties of the k-Body Embedded Unitary Ensemble of Random Matrices
We extend the recent study of the k-body embedded Gaussian ensembles by Benet et al. (Phys. Rev. Lett. 87 (2001) 101601-1 and Ann. Phys. 292 (2001) 67) and by Asaga et al. (cond-mat/0107363 and…
Z. Pluhar, H. A. WeidenmuellerNov 29, 2001
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Correlation functions for a Bose-Einstein condensate in the Bogoliubov approximation
In this article we introduce a differential equation for the first order correlation function G(1) of a Bose-Einstein condensate at T=0. The Bogoliubov approximation is used. Our approach points…
A. Montina, E. ArimondoNov 29, 2001
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Dynamical transitions in incommensurate systems
In the dynamics of the undamped Frenkel-Kontorova model with kinetic terms, we find a transition between two regimes, a floating incommensurate and a pinned incommensurate phase. This behavior is…
L. Consoli, H. Knops, A. FasolinoNov 28, 2001
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Exact results on the dynamics of multi-component Bose-Einstein condensate
We study the time-evolution of the two dimensional multi-component Bose-Einstein condensate in an external harmonic trap with arbitrary time-dependent frequency. We show analytically that the…
Pijush K. GhoshNov 28, 2001
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A practical guide to computer simulations
Here practical aspects of conducting research via computer simulations are discussed. The following issues are addressed: software engineering, object-oriented software development, programming…
Alexander K. Hartmann, Heiko RiegerNov 28, 2001
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Renormalization Group Analysis of a Confined, Interacting Bose Gas
The renormalization group is not only a powerful method for describing universal properties of phase transitions but it is also useful for evaluating non- universal properties beyond mean-field…
Gernot Alber, Georgios MetikasNov 27, 2001
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On Possible Coexistence of Superconductivity and Charge Density Wave in Hole Doped C60
We study metallic behavior and superconductivity in C60 materials in terms of a tight binding model characterized by an intramolecular, nonretarded attraction. It was shown previously that, at…
Sanjoy K. SarkerNov 26, 2001
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Spin Splitting in Quantum Wires with Perturbed Axial Symmetry
We investigate theoretically perturbations to the confining potential capable of lifting spin degeneracy in axially symmetric quasi-one-dimensional electron gases with the spin-orbit interaction. The…
A. D. Bochevarov, K. IlyenkoNov 26, 2001
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Derivatives of the fixed-node energy
We present quantum Monte Carlo calculations of total energy derivatives, consistently performed in the fixed-node approximation. Contributions from nodal displacements, neglected or approximated in…
S. De Palo, S. Moroni, S. BaroniNov 26, 2001
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A p-Spin Interaction Ashkin-Teller Spin-Glass Model
A p-spin interaction Ashkin-Teller spin glass, with three independent Gaussian probability distributions for the exchange interactions, is studied by means of the replica method. A simple phase…
I. S. Queiroz, F. A. da Costa, F. D. NobreNov 26, 2001
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Bushes of normal modes - new dynamical objects in nonlinear mechanical systems with discrete symmetry
Bushes of normal modes represent exact mathematical objects describing specific dynamical regimes in nonlinear mechanical systems with point or space symmetry. In the present paper, we outline the…
George M. Chechin, Alexandr V. Gnezdilov, Vladimir P. Sakhnenko et al.Nov 25, 2001
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Remarks on nonlinear Schroedinger equations with harmonic potential
Bose-Einstein condensation is usually modeled by nonlinear Schroedinger equations with harmonic potential. We study the Cauchy problem for these equations. We show that the local problem can be…
Remi CarlesNov 24, 2001
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