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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physica A: Statistical Mechanics and its Applications 112 (1982), S. 361-392 
    ISSN: 0378-4371
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physica A: Statistical Mechanics and its Applications 118 (1983), S. 445 
    ISSN: 0378-4371
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of statistical physics 79 (1995), S. 117-164 
    ISSN: 1572-9613
    Keywords: Aerogels ; fractal percolation ; surface tension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We investigate the behavior of various spin-systems that are subject to the highly correlated and extremely diluted quenched disorder as provided by the fractal aerogel model. For these systems, it is (easily) established that, at all temperatures, the free energy is identical to that of the corresponding uniform system. The surface tension, however, behaves quite differently. Foremost, at any fixed temperature corresponding to the low temperature phase in the uniform system, there is a non-trivial curve in the aerogel phase plane dividing high-temperature behavior (zero surface tension) from low-temperature behavior (positive surface tension). The fractal aerogel has two distinctive phases in its own right: gel and sol. In the gel phase, the spin system has zero surface tension at all temperatures. In one region of the sol phase, the surface tension is shown to be equal to its value in the uniform system. Since part of this region borders on the gel phase, a certain portion of the sol/gel phase boundary is also the dividing line between high- and low-temperature behavior. Evidently, in this case, the surface tension is discontinuous at the phase boundary. on the other hand, there are well-defined length scales that diverge as the phase boundary is approached. This demonstrates an absence of scaling in these systems.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of statistical physics 93 (1998), S. 17-32 
    ISSN: 1572-9613
    Keywords: Cluster methods ; external fields ; RFIM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A graphical representation based on duplication is developed that is suitable for the study of Ising systems in external fields. Two independent replicas of the Ising system in the same field are treated as a single four-state (Ashkin–Teller) model. Bonds in the graphical representation connect the Ashkin–Teller spins. For ferromagnetic systems it is proved that ordering is characterized by percolation in this representation. The representation leads immediately to cluster algorithms; some applications along these lines are discussed.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of statistical physics 34 (1984), S. 477-495 
    ISSN: 1572-9613
    Keywords: Diffusion ; random media ; fluctuations ; long time tails ; Lorentz model ; hopping models ; velocity correlation functions ; mode coupling theory ; diffusion coefficients ; Burnett coefficients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Diffusion of moving particles in stationary disordered media is studied using a phenomenological mode-coupling theory. The presence of disorder leads to a generalized diffusion equation, with memory kernels having power law long time tails. The velocity autocorrelation function is found to decay like t−(d/2+1), while the time correlation function associated with the super-Burnett coefficient decays liket −d/2 for long times. The theory is applicable to a wide variety of dynamical and stochastic systems including the Lorentz gas and hopping models. We find new, general expressions for the coefficients of the long time tails which agree with previous results for exactly solvable hopping models and with the low-density results obtained for the Lorentz gas. Finally we mention that if the moving particles are charged, then the long time tails imply that there is an ω d/2 contribution to the low-frequency part of the frequency-dependent electrical conductivity.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of statistical physics 35 (1984), S. 413-442 
    ISSN: 1572-9613
    Keywords: Long time tails ; random media ; mode-coupling theory ; Lorentz models ; random walks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In a previous paper we developed a mode-coupling theory to describe the long time properties of diffusion in stationary, statistically homogeneous, random media. Here the general theory is applied to deterministic and stochastic Lorentz models and several hopping models. The mode-coupling theory predicts that the amplitudes of the long time tails for these systems are determined by spatial fluctuations in a coarse-grained diffusion coefficient and a coarse-grained free volume. For one-dimensional models these amplitudes can be evaluated, and the mode-coupling theory is shown to agree with exact solutions obtained for these models. For higher-dimensional Lorentz models the formal theory yields expressions which are difficult to evaluate. For these models we develop an approximation scheme based upon projecting fluctuations in the diffusion coefficient and free volume onto fluctuations in the density of scatterers.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of statistical physics 64 (1991), S. 541-578 
    ISSN: 1572-9613
    Keywords: Self-avoiding walks ; disordered systems ; real-space renormalization group ; percolation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The self-avoiding walk in a quenched random environment is studied using real-space and field-theoretic renormalization and “Flory” arguments. These methods indicate that the system is described, ford〈d c =4, and, for large disorder ford〉d c , by a strong disorder fixed point corresponding to a “glass” state in which the polymer is confined to the lowest energy path. This fixed point is characterized by scaling laws for the size of the walk,L∼N pζ withN the number of steps, and the fluctuations in the free energy,Αf∼L pζ. The bound 1/ζ-ω⩽d/2 is obtained. Exact results on hierarchical lattices yieldζ〉ζ pure and suggests that this inequality holds ford=2 and 3, althoughζ=ζ pure cannot be excluded, particularly ford=2. Ford〉d c there is a transition between strong and weak disorder phases at whichζ=ζ pure. The strong-disorder fixed point for SAWs on percolation clusters is discussed. The analogy with directed walks is emphasized.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of statistical physics 87 (1997), S. 1245-1252 
    ISSN: 1572-9613
    Keywords: Lorentz lattice gas ; computational complexity ; parallel computation ; logical depth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The Lorentz lattice gas is studied from the perspective of computational complexity theory. It is shown that using massive parallelism, particle trajectories can be simulated in a time that scales logarithmically in the length of the trajectory. This result characterizes the “logical depth” of the Lorentz lattice gas and allows us to compare it to other models in statistical physics.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of statistical physics 94 (1999), S. 53-66 
    ISSN: 1572-9613
    Keywords: ising model ; percolation ; mean-field theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The q=2 random cluster model is studied in the context of two mean-field models: the Bethe lattice and the complete graph. For these systems, the critical exponents that are defined in terms of finite clusters have some anomalous values as the critical point is approached from the high-density side, which vindicates the results of earlier studies. In particular, the exponent γ~′ which characterizes the divergence of the average size of finite clusters is 1/2, and ν~′, the exponent associated with the length scale of finite clusters, is 1/4. The full collection of exponents indicates an upper critical dimension of 6. The standard mean field exponents of the Ising system are also present in this model (ν′=1/2, γ′=1), which implies, in particular, the presence of two diverging length-scales. Furthermore, the finite cluster exponents are stable to the addition of disorder, which, near the upper critical dimension, may have interesting implications concerning the generality of the disordered system/correlation length bounds.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of low temperature physics 74 (1989), S. 231-261 
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Superfluid films adsorbed on a cylindrical surface are studied. The superfluid density is calculated using a modification of the Kosterlitz-Thouless theory. There is no vortex unbinding transition because the vortex interaction is linear on long length scales. Thus the superfluid areal density, defined in terms of the real part of a response function, is nonzero for all T〈Tλ. The superfluid density is anisotropic, differing for axial and azimuthal flows. Dissipation due to vortex motion is considered. The periodicity of the substrate leads to a zero frequency dissipation mechanism for flows in the axial direction.
    Type of Medium: Electronic Resource
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