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The bond percolation problem is studied by the Monte Carlo method on a two-dimensional square lattice of 2 X lo6 bonds. Through the inclusion of a ghost field h, we obtain the generating function (the percolation analogue of the Gibbs free energy), percolation probability (the analogue of the spontaneous magnetisation), and mean cluster size ('isothermal susceptibility') as functions of two 'thermodynamic' variables, c = ( p , -p ) / p c and h. We discuss the non-trivial problems associated with the identification of the singular parts of these functions. We demonstrate that scaling holds for all three 'thermodynamic' functions within a rather large 'scaling region'.
Journal of Physics A: Mathematical and General, 1978
The bond percolation problem is studied by the Monte Carlo method on a two-dimensional square lattice of 2 X lo6 bonds. Through the inclusion of a ghost field h, we obtain the generating function (the percolation analogue of the Gibbs free energy), percolation probability (the analogue of the spontaneous magnetisation), and mean cluster size ('isothermal susceptibility') as functions of two 'thermodynamic' variables, c = ( p , -p ) / p c and h. We discuss the non-trivial problems associated with the identification of the singular parts of these functions. We demonstrate that scaling holds for all three 'thermodynamic' functions within a rather large 'scaling region'.
2001
Percolation models with multiple percolating clusters have attracted much attention in recent years. Here we use Monte Carlo simulations to study bond percolation on L_1× L_2 planar random lattices, duals of random lattices, and square lattices with free and periodic boundary conditions, in vertical and horizontal directions, respectively, and with various aspect ratio L_1/L_2. We calculate the probability for the appearance of n percolating clusters, W_n, the percolating probabilities, P, the average fraction of lattice bonds (sites) in the percolating clusters, <c^b>_n (<c^s>_n), and the probability distribution function for the fraction c of lattice bonds (sites), in percolating clusters of subgraphs with n percolating clusters, f_n(c^b) (f_n(c^s)). Using a small number of nonuniversal metric factors, we find that W_n, P, <c^b>_n (<c^s>_n), and f_n(c^b) (f_n(c^s)) for random lattices, duals of random lattices, and square lattices have the same universal fi...
Chaos: An Interdisciplinary Journal of Nonlinear Science
We report on the exact treatment of a random-matrix representation of a bond-percolation model on a square lattice in two dimensions with occupation probability p. The percolation problem is mapped onto a random complex matrix composed of two random real-valued matrices of elements +1 and −1 with probability p and 1 − p, respectively. We find that the onset of percolation transition can be detected by the emergence of power-law divergences due to the coalescence of the first two extreme eigenvalues in the thermodynamic limit. We develop a universal finite-size scaling law that fully characterizes the scaling behavior of the extreme eigenvalue's fluctuation in terms of a set of universal scaling exponents and amplitudes. We make use of the relative entropy as an index of the disparity between two distributions of the first and second-largest extreme eigenvalues to show that its minimum underlies the scaling framework. Our study may provide an inroad for developing new methods and algorithms with diverse applications in machine learning, complex systems, and statistical physics.
We introduce anisotropic bond percolation in which there exist different occupation probabilities for bonds placed in different coordinate directions. We study in detail a d-dimensional hypercubical lattice, with probabilities p I for bonds within (d -1)-dimensional layers perpendicular to the z direction, and p11= Rp, for bonds parallel to z. For this model, we calculate low-density series for the mean size S, in both two and three dimensions for arbitrary values of the anisotropy parameter R. We find that in the limit 1/R + 0, the model exhibits crossover between 1 and d-dimensional critical behaviour, and that the mean-size function scales in 1/R. From both exact results and series analysis, we derive that the crossover exponent (=&) is 1 for all d, and that the divergence of successive derivatives of S with respect to 1 / R increases with a constant gap equal to 1 in two and three dimensions. In the opposite limit R + 0, crossover between d -1 and d-dimensional order occurs, and from our analysis of the three-dimensional series it appears that here the crossover exponent &-I is not equal to the two-dimensional mean-size exponent. This feature is in contrast with the corresponding situation in thermal critical phenomena where 6 d -l does equal the susceptibility exponent in two dimensions. Finally, our analysis appears to confirm that the value of the mean-size exponent is independent of anisotropy in accordance with universality.
Communications in Mathematical Physics, 1990
The triangle condition for percolation states that ]Γ τ(0,x) τ(x,y) χ,y-τ (y, 0) is finite at the critical point, where τ (x, y) is the probability that the sites x and y are connected. We use an expansion related to the lace expansion for a self-avoiding walk to prove that the triangle condition is satisfied in two situations: (i) for nearest-neighbour independent bond percolation on thê /-dimensional hypercubic lattice, if d is sufficiently large, and (ii) in more than six dimensions for a class of "spread-out" models of independent bond percolation which are believed to be in the same universality class as the nearest-neighbour model. The class of models in (ii) includes the case where the bond occupation probability is constant for bonds of length less than some large number, and is zero otherwise. In the course of the proof an infrared bound is obtained. The triangle condition is known to imply that various critical exponents take their mean-field (Bethe lattice) values (y = β = 1, δ = Δ t = 2, ί ^ 2) and that the percolation density is continuous at the critical point. We also prove that v 2 = 1/2 in (i) and (ii), where v 2 is the critical exponent for the correlation length.
Eprint Arxiv 0806 3020, 2008
The Ising model at inverse temperature $\beta$ and zero external field can be obtained via the Fortuin-Kasteleyn (FK) random-cluster model with $q=2$ and density of open edges $p=1-e^{-\beta}$ by assigning spin +1 or -1 to each vertex in such a way that (1) all the vertices in the same FK cluster get the same spin and (2) +1 and -1 have equal probability. We generalize the above procedure by assigning spin +1 with probability $r$ and -1 with probability $1-r$, with $r \in [0,1]$, while keeping condition (1). For fixed $\beta$, this generates a dependent (spin) percolation model with parameter $r$. We show that, on the triangular lattice and for $\beta<\beta_c$, this model has a percolation phase transition at $r=1/2$, corresponding to the Ising model. This sheds some light on the conjecture that the high temperature Ising model on the triangular lattice is in the percolation universality class and that its scaling limit can be described in terms of SLE$_6$. We also prove uniqueness of the infinite +1 cluster for $r>1/2$, sharpness of the percolation phase transition (by showing exponential decay of the cluster size distribution for $r<1/2$), and continuity of the percolation function for all $r \in [0,1]$.
Rsa, 1997
We address the question of finite-size scaling in percolation by studying bond percolation in a finite box of side length n, both in two and in higher dimensions. In dimension d = 2, we obtain a complete characterization of finite-size scaling. In dimensions d > 2, we establish the same results under a set of hypotheses related to so-called scaling and hyperscaling postulates which are widely believed to hold up to d = 6.
Journal of Physics A: Mathematical and General, 1996
We have derived long series expansions of the percolation probability for site, bond and site-bond percolation on the directed triangular lattice. For the bond problem we have extended the series from order 12 to 51 and for the site problem from order 12 to 35. For the site-bond problem, which has not been studied before, we have derived the series to order 32. Our estimates of the critical exponent β are in full agreement with results for similar problems on the square lattice, confirming expectations of universality. For the critical probability and exponent we find in the site case: q c = 0.4043528 ± 0.0000010 and β = 0.27645 ± 0.00010; in the bond case: q c = 0.52198 ± 0.00001 and β = 0.2769 ± 0.0010; and in the site-bond case: q c = 0.264173 ± 0.000003 and β = 0.2766 ± 0.0003. In addition we have obtained accurate estimates for the critical amplitudes. In all cases we find that the leading correction to scaling term is analytic, i.e., the confluent exponent ∆ = 1.
Physical Review B, 1981
A generalized model of percolation encompassing both the usual model, in which bonds are occupied with probability p and are vacant with probability (1−p), and the model appropriate to the statistics of lattice animals, in which the fugacity for occupied bonds is p and that for unoccupied bonds is unity, is formulated. Within this model we discuss the crossover between the two problems and we study the statistics of large clusters. We determine the scaling form which the distribution function for the number of clusters with a given number of sites n assumes as a function of both n and p. For p near p c we find that the distribution function depends on percolation exponents for u=n(p c −p) Δ p small, where Δ p is a crossover exponent, and on exponents appropriate to the lattice-animals problem for large values of u. We thus have displayed the relation between the two limits and show conclusively that the lattice-animals exponents cannot be obtained by any simple scaling arguments from the percolation exponents. We also demonstrate that essential singularities in the cluster distribution functions for p>p c arise from metastable states of the Potts model.
Physical Review E, 2014
We derive the critical nearest-neighbor connectivity g n as 3/4, 3(7 − 9p tri c)/4(5 − 4p tri c), and 3(2 + 7p tri c)/ 4(5 − p tri c) for bond percolation on the square, honeycomb, and triangular lattice, respectively, where p tri c = 2 sin(π/18) is the percolation threshold for the triangular lattice, and confirm these values via Monte Carlo simulations. On the square lattice, we also numerically determine the critical next-nearest-neighbor connectivity as g nn = 0.687 500 0(2), which confirms a conjecture by Mitra and Nienhuis [J. Stat. Mech. (2004) P10006], implying the exact value g nn = 11/16. We also determine the connectivity on a free surface as g surf n = 0.625 000 1(13) and conjecture that this value is exactly equal to 5/8. In addition, we find that at criticality, the connectivities depend on the linear finite size L as ∼ L yt −d , and the associated specific-heat-like quantities C n and C nn scale as ∼ L 2yt −d ln(L/L 0), where d is the lattice dimensionality, y t = 1/ν the thermal renormalization exponent, and L 0 a nonuniversal constant. We provide an explanation of this logarithmic factor within the theoretical framework reported recently by Vasseur et al.
Physical Review C, 1997
We examine the average cluster distribution as a function of lattice probability for a very small (Lϭ6) lattice and determine the scaling function of three-dimensional percolation. The behavior of the second moment, calculated from the average cluster distribution of Lϭ6 and Lϭ63 lattices, is compared to power-law behavior predicted by the scaling function. We also examine the finite-size scaling of the critical point and the size of the largest cluster at the critical point. This analysis leads to estimates of the critical exponent and the ratio of critical exponents /. ͓S0556-2813͑97͒02703-9͔
Communications in Theoretical Physics, 2015
We have investigated both site and bond percolation on two-dimensional lattice under the random rule and the product rule respectively. With the random rule, sites or bonds are added randomly into the lattice. From two candidates picked randomly, the site or bond with the smaller size product of two connected clusters is added when the product rule is taken. Not only the size of the largest cluster but also its size jump are studied to characterize the universality class of percolation. The finite-size scaling forms of giant cluster size and size jump are proposed and used to determine the critical exponents of percolation from Monte Carlo data. It is found that the critical exponents of both size and size jump in random site percolation are equal to that in random bond percolation. With the random rule, site and bond percolation belong to the same universality class. We obtain the critical exponents of the site percolation under the product rule, which are different from that of bo...
The percolation problem is solved exactly in one dimension. The functions obtained bear a strong resemblance to those of the n-vector model on the same lattice.
Cluster statistics obtained by the Monte Carlo method for percolation processes in systems of dimensionality two to seven are analysed for the percolation analogue of the thermodynamic equation of state, thus complementing the work of paper I on cluster numbers. In particular, we calculate the scaling functions for the analogues of the thermodynamic potentials and their derivatives, and investigate their dependence on dimension d. We are guided by the two exactly soluble limits of d = 1 and the Bethe lattice ( d =a). The scaling region, where a good degree of data collapsing can be observed, is investigated in terms of the two 'thermodynamic' variables, one of which is analogous to the temperature and the other to the magnetic field. This region is found to be comparatively large and symmetrical in two dimensions, but considerably smaller in higher dimensions. In addition, we find that the characteristic forms of the scaling functions are closely related to the 'thermodynamic' stability conditions. Finally, we analyse the logarithmic corrections to the scaled equation of state at the upper marginal dimension, d, = 6 , and a numerical demonstration of the significance of the logarithmic corrections is presented in terms of data collapsing.
Physical Review B, 1980
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Physical Review B, 1990
Series expansions for general moments of the bond-percolation cluster-size distribution on hypercubic lattices to 15th order in the concentration have been obtained. This is one more than the previously published series for the mean cluster size in three dimensions and four terms more for higher moments and higher dimensions. Critical exponents, amplitude ratios, and thresholds have been calculated from these and other series by a variety of independent analysis techniques. A comprehensive summary of extant estimates for exponents, some universal amplitude ratios, and thresholds for percolation in all dimensions is given, and our results are shown to be in excellent agreement with the ε expansion and some of the most accurate simulation estimates. We obtain threshold values of 0.2488±0.0002 and 0.180 25±0.000 15 for the three-dimensional bond problem on the simple-cubic and body-centered-cubic lattices, respectively, and 0.160 05±0.000 15 and 0.118 19±0.000 04, for the hypercubic bond problem in four and five dimensions, respectively. Our direct exponent estimates are γ=1.805±0.02, 1.435±0.015, and 1.185±0.005, and β=0.405±0.025, 0.639±0.020, and 0.835±0.005 in three, four, and five dimensions, respectively.
2015
This chapter is based on [10] with Rob van den Berg. We consider (near-)critical percolation on the square lattice. Let M n be the size of the largest open cluster contained in the box [−n, n] 2 , and let π(n) be the probability that there is an open path from O to the boundary of the box. It is well-known (see [17]) that for all 0 < a < b the probability that M n is smaller than an 2 π(n) and the probability that M n is larger than bn 2 π(n) are bounded away from 0 as n → ∞. It is a natural question, which arises for instance in the study of so-called frozenpercolation processes, if a similar result holds for the probability that M n is between an 2 π(n) and bn 2 π(n). By a suitable partition of the box, and a careful construction involving the building blocks, we show that the answer to this question is armative. The`sublinearity' of 1/π(n) appears to be essential for the argument. percolation and FK-Ising This chapter is based on [20] with Federico Camia and Demeter Kiss. Under some general assumptions we construct the scaling limit of open clusters and their associated counting measures in a class of two-dimensional percolation models. Our results apply, in particular, to critical Bernoulli site percolation on the triangular lattice. We also provide conditional results for the critical FK-Ising model on the square lattice. Fundamental properties of the scaling limit, such as conformal covariance, are explored. Applications such as the scaling limit of the largest cluster in a bounded domain and a geometric representation of the magnetization eld for the critical Ising model are presented.
Physical Review B, 1984
A method for generalizing bond-percolation problems to include the possibility of infinite-range (equivalent-neighbor) bonds is presented. On Bravais lattices the crossover from nonclassical to classical (mean-field) percolation criticality in the presence of such bonds is described. The Cayley tree with nearest-neighbor and equivalent-neighbor bonds is solved exactly, and a nonuniversal line of percolation transitions with exponents dependent on nearest-neighbor bond occupation probability is observed. Points of logarithmic and exponential singularity are also encountered, and the behavior is interpreted as dimensional reduction due to the breaking of translational invariance by bonds of Cayley-tree connectivity.
Journal of Physics A: Mathematical and General, 1980
We present a calculation of the bond percolation problem in a square lattice in presence of a 'magnetic field', using the position space renormalisation group and cells of dimension b x b, where b runs from 2 up to 5. Due to symmetry, the calculation splits into two parts, one determining the 'thermal' exponent U and the other, the 'magnetic' exponent 7. For the largest cell in each case, we get v = 1.355 (b = 5) and 7 = 0.244 (b = 4), in good agreement with series results of Dunn et al. Comments are made on the extrapolation of the results to b = CO.
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