5,416 research outputs found
Slow Forcing in the Projective Dynamics Method
We provide a proof that when there is no forcing the recently introduced
projective dynamics Monte Carlo algorithm gives the exact lifetime of the
metastable state, within statistical uncertainties. We also show numerical
evidence illustrating that for slow forcing the approach to the zero-forcing
limit is rather rapid. The model studied numerically is the 3-dimensional
3-state Potts ferromagnet.Comment: 1 figure, invited submission to CCP'98 conference, submitted to
Computer Physics Communication
Hysteresis loop areas in kinetic Ising models: Effects of the switching mechanism
Experiments on ferromagnetic thin films have measured the dependence of the
hysteresis loop area on the amplitude and frequency of the external field,
=, and approximate agreement with numerical simulations of
Ising models has been reported. Here we present numerical and theoretical
calculations of in the low-frequency regime for two values of ,
which bracket a temperature and system-size dependent crossover field. Our
previous Monte Carlo studies have shown that the hysteretic response of the
kinetic Ising model is qualitatively different for amplitudes above and below
this crossover field. Using droplet theory, we derive analytic expressions for
the low-frequency asymptotic behavior of the hysteresis loop area. In both
field regimes, the loop area exhibits an extremely slow approach to an
asymptotic, logarithmic frequency dependence of the form . Our results are relevant to the interpretation of data
from experiments and simulations, on the basis of which power-law exponents for
the hysteresis-loop area have been reported.Comment: 9 pages including 3 figures. Submitted as a manuscript for the 7th
Joint MMM-Intermag conference. To be published in the Journal of Applied
Physics and the IEEE Transactions on Magnetics. Contains 1 updated figure and
revised tex
A rejection-free Monte Carlo method for the hard-disk system
We construct a rejection-free Monte Carlo method for the hard-disk system.
Rejection-free Monte Carlo methods preserve the time-evolution behavior of the
standard Monte Carlo method, and this relationship is confirmed for our method
by observing nonequilibrium relaxation of a bond-orientational order parameter.
The rejection-free method gives a greater computational efficiency than the
standard method at high densities. The rejection free method is implemented in
a shrewd manner using optimization methods to calculate a rejection probability
and to update the system. This method should allow an efficient study of the
dynamics of two-dimensional solids at high density.Comment: 8 pages, 9 figures. This paper has been combined into the
cond-mat/0508652, and published in Phys. Rev.
A projection method for statics and dynamics of lattice spin systems
A method based on Monte Carlo sampling of the probability flows projected
onto the subspace of one or more slow variables is proposed for investigation
of dynamic and static properties of lattice spin systems. We illustrate the
method by applying it, with projection onto the order-parameter subspace, to
the three-dimensional 3-state Potts model in equilibrium and to metastable
decay in a three-dimensional 3-state kinetic Potts model.Comment: 4 pages, 3 figures, RevTex, final version to appear in Phys. Rev.
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