58 research outputs found
Pressure-temperature phase diagrams of selenium and sulfur in terms of Patashinski model
The pressure - temperature phase diagrams of Se and S are calculated. Both
melting and polymorphous phase transition are described in the frames of
statistical Patashinski model. The results are in good agreement with
experimental data of Brazhkin et. al.Comment: 3 eps figures, will appear in Physica A, mail to first author
[email protected]
Nonequilibrium Critical Phenomena
We discuss the non-equilibrium critical phenomena in liquids, and the models
for these phenomena based on local equilibrium and extended scaling
assumptions. Special situations are proposed for experimental tests of the
theory. Near-critical steady and transient states are reviewed. In a
near-critical steady state characterized by a temperature gradient, the theory
predicts strong nonequilibrium fluctuations at very large length scales. Close
to the critical point, this results in a nonlinear regime of heat conductivity.
A transient non-equilibrium state triggered by a rapid and large spatially
uniform perturbation of the critical liquid is considered. A step away from
criticality generates a free field with strong and decaying correlations in
initial state, while a step towards criticality initiates the increase of
fluctuations and of their correlation at the large scale edge of the critical
range. The approach to equilibrium is characterized by an equilibration length
\Lambda_eq that depends on time t. The theory predicts a power law approach of
the temperature to the new equilibrium; the new critical exponents depend on
whether the temperature is initially increased or decreased
Anomalous fluctuations in phases with a broken continuous symmetry
It is shown that the Goldstone modes associated with a broken continuous
symmetry lead to anomalously large fluctuations of the zero field order
parameter at any temperature below T_c. In dimensions 2<d<4, the variance of
the extensive spontaneous magnetization scales as L^4 with the system size L,
independent of the order parameter dynamics. The anomalous scaling is a
consequence of the 1/q^{4-d} divergence of the longitudinal susceptibility. For
ground states in two dimensions with Goldstone modes vanishing linearly with
momentum, the dynamical susceptibility contains a singular contribution
(q^2-\omega^2/c^2)^{-1/2}. The dynamic structure factor thus exhibits a
critical continuum above the undamped spin wave pole, which may be detected by
neutron scattering in the N\'eel-phase of 2D quantum antiferromagnets.Comment: final version, minor change
Surface rearrangement at complex adsorbate-substrate interfaces
On the basis of the information theory approach we propose a novel
statistical scheme for analyzing the evolution of coupled adsorbate-substrate
systems, in which the substrate undergoes the adsorbate-induced
transformations. A relation between the substrate morphology and the adsorbate
thermodynamic state is established. This allows one to estimate the surface
structure in terms of incomplete experimental information and the one
concerning the adsorbate thermodynamic response to the structural
modifications.Comment: 5 pages, 3 figure
Probability Density, Diagrammatic Technique, and Epsilon Expansion in the Theory of Wave Turbulence
We apply the methods of Field Theory to study the turbulent regimes of
statistical systems. First we show how one can find their probability
densities. For the case of the theory of wave turbulence with four-wave
interaction we calculate them explicitly and study their properties. Using
those densities we show how one can in principle calculate any correlation
function in this theory by means of direct perturbative expansion in powers of
the interaction. Then we give the general form of the corrections to the
kinetic equation and develop an appropriate diagrammatic technique. This
technique, while resembling that of theory, has many new
distinctive features. The role of the parameter is played here
by the parameter where is the
dimension of the interaction, is the space dimension, is the
dimension of the energy spectrum and is the ``classical'' wave density
dimension. If then the Kolmogorov index is exact, and if then we expect it to be modified by the interaction. For a small
negative number, and a special form of the interaction we compute
this modification explicitly with the additional assumption of the irrelevance
of the IR divergencies which still needs to be verified.Comment: 26 pages, PUPT-146
The free energy in a magnetic field and the universal scaling equation of state for the three-dimensional Ising model
We have substantially extended the high-temperature and low-magnetic-field
(and the related low-temperature and high-magnetic-field) bivariate expansions
of the free energy for the conventional three-dimensional Ising model and for a
variety of other spin systems generally assumed to belong to the same critical
universality class. In particular, we have also derived the analogous
expansions for the Ising models with spin s=1,3/2,.. and for the lattice
euclidean scalar field theory with quartic self-interaction, on the simple
cubic and the body-centered cubic lattices. Our bivariate high-temperature
expansions, which extend through K^24, enable us to compute, through the same
order, all higher derivatives of the free energy with respect to the field,
namely all higher susceptibilities. These data make more accurate checks
possible, in critical conditions, both of the scaling and the universality
properties with respect to the lattice and the interaction structure and also
help to improve an approximate parametric representation of the critical
equation of state for the three-dimensional Ising model universality class.Comment: 22 pages, 10 figure
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