519 research outputs found
Nature of crossover from classical to Ising-like critical behavior
We present an accurate numerical determination of the crossover from
classical to Ising-like critical behavior upon approach of the critical point
in three-dimensional systems. The possibility to vary the Ginzburg number in
our simulations allows us to cover the entire crossover region. We employ these
results to scrutinize several semi-phenomenological crossover scaling functions
that are widely used for the analysis of experimental results. In addition we
present strong evidence that the exponent relations do not hold between
effective exponents.Comment: 4 pages RevTeX 3.0/3.1, 4 Encapsulated PostScript figures. Uses
epsf.sty. Also available as PDF file at
http://www.cond-mat.physik.uni-mainz.de/~luijten/erikpubs.htm
Out of Equilibrium Characteristics of a Forced Translocating Chain through a Nanopore
Polymer translocation through a nano-pore in a thin membrane is studied using
a coarse-grained bead-spring model and Langevin dynamics simulation with a
particular emphasis to explore out of equilibrium characteristics of the
translocating chain. We analyze the out of equilibrium chain conformations both
at the and the side separately either as a function of the time
during the translocation process or as as function of the monomer index
inside the pore. A detailed picture of translocation emerges by monitoring the
center of mass of the translocating chain, longitudinal and transverse
components of the gyration radii and the end to end vector. We observe that
polymer configurations at the side are distinctly different from those at
the side. During the translocation, and immediately afterwards, the
chain is clearly out of equilibrium, as different parts of the chain are
characterized by a series of effective Flory exponents. We further notice that
immediately after the translocation the last set of beads that have just
translocated take a relatively compact structure compared to the first set of
beads that translocated earlier, and the chain immediately after translocation
is described by an effective Flory exponent . The analysis of
these results is further strengthened by looking at the conformations of chain
segments of equal length as they cross from the to the side, We
discuss implications of these results to the theoretical estimates and
numerical simulation studies of the translocation exponent reported by various
groups.Comment: 35 pages, 16 figures. Submitted to Phys. Rev.
The High Temperature Dynamics of a mean field Potts glass
We use Monte Carlo simulations to investigate the dynamical properties of the
infinite range 10 states Potts glass. By analyzing the spin autocorrelation
function for system sizes up to N=2560, we show that strong finite size effects
are present around the predicted dynamical transition temperature. The
autocorrelation function shows strong self-averaging at high temperatures,
whereas close to the dynamical transition they show the lack of self-averaging.Comment: 7 pages of Latex, 4 figure
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