30,569 research outputs found
Critical behavior of an absorbing phase transition in an interacting monomer-dimer model
We study a monomer-dimer model with repulsive interactions between the same
species in one dimension. With infinitely strong interactions the model
exhibits a continuous transition from a reactive phase to an inactive phase
with two equivalent absorbing states. Static and dynamic Monte Carlo
simulations show that the critical behavior at the transition is different from
the conventional directed percolation universality class but is consistent with
that of the models with the mass conservation of modulo 2. The values of static
and dynamic critical exponents are compared with those of other models. We also
show that the directed percolation universality class is recovered when a
symmetry-breaking field is introduced.Comment: 9 pages, latex, 1 figure (one PS figure file upon request) (appear in
Physica A (1995): Proceeding of Statphys-Taipei-1995
Dynamic critical behaviors of three-dimensional XY models related to superconductors/superfluids
The dynamic critical exponent z is determined from numerical simulations for
the three-dimensional XY model subject to two types of dynamics, i.e.
relaxational dynamics and resistively shunted junction (RSJ) dynamics, as well
as for two different treatments of the boundary, i.e., periodic boundary
condition (PBC) and fluctuating twist boundary condition (FTBC). In case of
relaxational dynamics, finite size scaling at the critical temperature gives
for PBC and 1.5 for FTBC, while for RSJ dynamics is
obtained in both cases. The results are discussed in the context of
superfluid/superconductors and vortex dynamics, and are compared with what have
been found for other related models.Comment: 7 pages, 5 figures with europhys.sty, to appear in Europhys. Let
Dynamic critical exponent of two-, three-, and four-dimensional XY models with relaxational and resistively shunted junction dynamics
The dynamic critical exponent is determined numerically for the
-dimensional XY model (, and 4) subject to relaxational dynamics and
resistively shunted junction dynamics. We investigate both the equilibrium
fluctuation and the relaxation behavior from nonequilibrium towards
equilibrium, using the finite-size scaling method. The resulting values of
are shown to depend on the boundary conditions used, the periodic boundary
condition, and fluctuating twist boundary condition (FTBC), which implies that
the different treatments of the boundary in some cases give rise to different
critical dynamics. It is also found that the equilibrium scaling and the
approach to equilibrium scaling for the the same boundary condition do not
always give the same value of . The FTBC in conjunction with the finite-size
scaling of the linear resistance for both type of dynamics yields values of
consistent with expectations for superfluids and superconductors: , 3/2,
and 2 for , 3, and 4, respectively.Comment: 21 pages, 16 figures, final versio
Statistical mechanics of warm and cold unfolding in proteins
We present a statistical mechanics treatment of the stability of globular
proteins which takes explicitly into account the coupling between the protein
and water degrees of freedom. This allows us to describe both the cold and the
warm unfolding, thus qualitatively reproducing the known thermodynamics of
proteins.Comment: 5 pages, REVTex, 4 Postscript figure
Universality Class of Two-Offspring Branching Annihilating Random Walks
We analyze a two-offspring Branching Annihilating Random Walk ( BAW)
model, with finite annihilation rate. The finite annihilation rate allows for a
dynamical phase transition between a vacuum, absorbing state and a non-empty,
active steady state. We find numerically that this transition belongs to the
same universality class as BAW's with an even number of offspring, ,
and that of other models whose dynamic rules conserve the parity of the
particles locally. The simplicity of the model is exploited in computer
simulations to obtain various critical exponents with a high level of accuracy.Comment: 10 pages, tex, 4 figures uuencoded, also available upon reques
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