162 research outputs found
Equivalence of stationary state ensembles
We show that the contact process in an ensemble with conserved total particle
number, as simulated recently by Tome and de Oliveira [Phys. Rev. Lett. 86
(2001) 5463], is equivalent to the ordinary contact process, in agreement with
what the authors assumed and believed. Similar conserved ensembles and
equivalence proofs are easily constructed for other models.Comment: 5 pages, no figure
Simulating nanoscale dielectric response
We introduce a constrained energy functional to describe dielectric response.
We demonstrate that the local functional is a generalization of the long ranged
Marcus energy. Our re-formulation is used to implement a cluster Monte Carlo
algorithm for the simulation of dielectric media. The algorithm avoids solving
the Poisson equation and remains efficient in the presence of spatial
heterogeneity, nonlinearity and scale dependent dielectric properties.Comment: 4 pages, 2 figures. Revtex
Rigorous Proof of a Liquid-Vapor Phase Transition in a Continuum Particle System
We consider particles in , interacting via attractive
pair and repulsive four-body potentials of the Kac type. Perturbing about mean
field theory, valid when the interaction range becomes infinite, we prove
rigorously the existence of a liquid-gas phase transition when the interaction
range is finite but long compared to the interparticle spacing.Comment: 11 pages, in ReVTeX, e-mail addresses: [email protected],
[email protected], [email protected]
Ferrohydrodynamics: testing a new magnetization equation
A new magnetization equation recently derived from irreversible
thermodynamics is employed to the calculation of an increase of ferrofluid
viscosity in a magnetic field. Results of the calculations are compared with
those obtained on the basis of two well-known magnetization equations. One of
the two was obtained phenomenologically, another one was derived
microscopically from the Fokker-Planck equation. It is shown that the new
magnetization equation yields a quite satisfactory description of
magnetiviscosity in the entire region of magnetic field strength and the flow
vorticity. This equation turns out to be valid -- like the microscopically
derived equation but unlike the former phenomenological equation -- even far
from equilibrium, and so it should be recommended for further applications.Comment: 4 pages, 3 figures, Submitted to Phys. Rev.
Stochastic model for the dynamics of interacting Brownian particles
Using the scheme of mesoscopic nonequilibrium thermodynamics, we construct
the one- and two- particle Fokker-Planck equations for a system of interacting
Brownian particles. By means of these equations we derive the corresponding
balance equations. We obtain expressions for the heat flux and the pressure
tensor which enable one to describe the kinetic and potential energy
interchange of the particles with the heat bath. Through the momentum balance
we analyze in particular the diffusion regime to obtain the collective
diffusion coefficient in terms of the hydrodynamic and the effective forces
acting on the Brownian particles.Comment: latex fil
Fermionic field theory for directed percolation in (1+1) dimensions
We formulate directed percolation in (1+1) dimensions in the language of a
reaction-diffusion process with exclusion taking place in one space dimension.
We map the master equation that describes the dynamics of the system onto a
quantum spin chain problem. From there we build an interacting fermionic field
theory of a new type. We study the resulting theory using renormalization group
techniques. This yields numerical estimates for the critical exponents and
provides a new alternative analytic systematic procedure to study
low-dimensional directed percolation.Comment: 20 pages, 2 figure
Exact Results for Kinetics of Catalytic Reactions
The kinetics of an irreversible catalytic reaction on substrate of arbitrary
dimension is examined. In the limit of infinitesimal reaction rate
(reaction-controlled limit), we solve the dimer-dimer surface reaction model
(or voter model) exactly in arbitrary dimension . The density of reactive
interfaces is found to exhibit a power law decay for and a slow
logarithmic decay in two dimensions. We discuss the relevance of these results
for the monomer-monomer surface reaction model.Comment: 4 pages, RevTeX, no figure
Swimming of a linear chain with a cargo in an incompressible viscous fluid with inertia
Scattering series in mobility problem for suspensions
The mobility problem for suspension of spherical particles immersed in an
arbitrary flow of a viscous, incompressible fluid is considered in the regime
of low Reynolds numbers. The scattering series which appears in the mobility
problem is simplified. The simplification relies on the reduction of the number
of types of single-particle scattering operators appearing in the scattering
series. In our formulation there is only one type of single-particle scattering
operator.Comment: 11 page
Charge and Current Sum Rules in Quantum Media Coupled to Radiation
This paper concerns the equilibrium bulk charge and current density
correlation functions in quantum media, conductors and dielectrics, fully
coupled to the radiation (the retarded regime). A sequence of static and
time-dependent sum rules, which fix the values of certain moments of the charge
and current density correlation functions, is obtained by using Rytov's
fluctuational electrodynamics. A technique is developed to extract the
classical and purely quantum-mechanical parts of these sum rules. The sum rules
are critically tested in the classical limit and on the jellium model. A
comparison is made with microscopic approaches to systems of particles
interacting through Coulomb forces only (the non-retarded regime). In contrast
with microscopic results, the current-current correlation function is found to
be integrable in space, in both classical and quantum regimes.Comment: 19 pages, 1 figur
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