共查询到6条相似文献,搜索用时 15 毫秒
1.
R. Raghavan Christopher L. Henley Scott L. Arouh 《Journal of statistical physics》1997,86(3-4):517-550
We define two new models on the square lattice in which each allowed configuration is a superposition of a covering by white dimers and one by black dimers. Each model maps to a solid-on-solid (SOS) model in which the height field is two dimensional. Measuring the stiffness of the SOS fluctuations in the rough phase provides critical exponents of the dimer models. Using this height representation, we have performed Monte Carlo simulations. They confirm that each dimer model has critical correlations and belongs to a new universality class. In the dimer-loop model (which maps to a loop model) one height component is smooth, but has unusual correlated fluctuations; the other height component is rough. In the noncrossing-dimer model the heights are rough, having two different elastic constants; an unusual form of its elastic theory implies anisotropic critical correlations. 相似文献
2.
K. Oerding 《Journal of statistical physics》1995,78(3-4):893-916
Finite-size scaling effects of the Ising model with quenched random impurities are studied, focusing on critical dynamics. In contrast to the pure Ising model, disordered systems are characterized by continuous relaxation time spectra. Dynamic field theory is applied to compute the spectral densities of the magnetizationM(t) and ofM
2(t). In addition, universal cumulant ratios are calculated to second order in 1/4, where =4–d andd<4 denotes the spatial dimension. 相似文献
3.
4.
Absence of mass gap for a class of stochastic contour models 总被引:1,自引:0,他引:1
We study a class of Markovian stochastic processes in which the state space is a space of lattice contours and the elementary motions are local deformations. We show, under suitable hypotheses on the jump rates, that the infinitesimal generator has zero mass gap. This result covers (among others) the BFACF dynamics for fixed-endpoint self-avoiding walks and the Sterling-Greensite dynamics for fixed-boundary self-avoiding surfaces. Our models also mimic the Glauber dynamics for the low-temperature Ising model. The proofs are based on two new general principles: the minimum hitting-time argument and the mean (or mean-exponential) hitting-time argument. 相似文献
5.
We prove exponential convergence to equilibrium (L
2 geometric ergodicity) for a random walk with inward drift on a sub-Cayley rooted tree. This randomwalk model generalizes a Monte Carlo algorithm for the self-avoiding walk proposed by Berretti and Sokal. If the number of vertices of levelN in the tree grows asC
N
~
N
N
–1
, we prove that the autocorrelation time satisfies N2 N1+ 相似文献
6.
O. Kapikranian B. Berche Yu. Holovatch 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,56(2):93-105
We present an analytic approach to study
concurrent influence of quenched non-magnetic site-dilution and
finiteness of the lattice on the 2D XY model. Two significant
deeply connected features of this spin model are: a special type
of ordering (quasi-long-range order) below a certain temperature
and a size-dependent mean value of magnetisation in the
low-temperature phase that goes to zero (according to the
Mermin-Wagner-Hohenberg theorem) in the thermodynamic limit. We
focus our attention on the asymptotic behaviour of the spin-spin
correlation function and the probability distribution of
magnetisation. The analytic approach is based on the spin-wave
approximation valid for the low-temperature regime and an
expansion in the parameters which characterise the deviation from
completely homogeneous configuration of impurities. We further
support the analytic considerations by Monte Carlo simulations
performed for different concentrations of impurities and compare
analytic and MC results. We present as the main quantitative
result of the work the exponent of the spin-spin correlation
function power law decay. It is non universal depending not only
on temperature as in the pure model but also on concentration of
magnetic sites. This exponent characterises also the vanishing of
magnetisation with increasing lattice size. 相似文献