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This article may be too technical for most readers to understand.(March 2021) |
The percolation threshold is a mathematical concept in percolation theory that describes the formation of long-range connectivity in random systems. Below the threshold a giant connected component does not exist; while above it, there exists a giant component of the order of system size. In engineering and coffee making, percolation represents the flow of fluids through porous media, but in the mathematics and physics worlds it generally refers to simplified lattice models of random systems or networks (graphs), and the nature of the connectivity in them. The percolation threshold is the critical value of the occupation probability p, or more generally a critical surface for a group of parameters p1, p2, ..., such that infinite connectivity ( percolation ) first occurs. [1]
The most common percolation model is to take a regular lattice, like a square lattice, and make it into a random network by randomly "occupying" sites (vertices) or bonds (edges) with a statistically independent probability p. At a critical threshold pc, large clusters and long-range connectivity first appear, and this is called the percolation threshold. Depending on the method for obtaining the random network, one distinguishes between the site percolation threshold and the bond percolation threshold. More general systems have several probabilities p1, p2, etc., and the transition is characterized by a critical surface or manifold. One can also consider continuum systems, such as overlapping disks and spheres placed randomly, or the negative space (Swiss-cheese models).
To understand the threshold, you can consider a quantity such as the probability that there is a continuous path from one boundary to another along occupied sites or bonds—that is, within a single cluster. For example, one can consider a square system, and ask for the probability P that there is a path from the top boundary to the bottom boundary. As a function of the occupation probability p, one finds a sigmoidal plot that goes from P=0 at p=0 to P=1 at p=1. The larger the square is compared to the lattice spacing, the sharper the transition will be. When the system size goes to infinity, P(p) will be a step function at the threshold value pc. For finite large systems, P(pc) is a constant whose value depends upon the shape of the system; for the square system discussed above, P(pc)=1⁄2 exactly for any lattice by a simple symmetry argument.
There are other signatures of the critical threshold. For example, the size distribution (number of clusters of size s) drops off as a power-law for large s at the threshold, ns(pc) ~ s−τ, where τ is a dimension-dependent percolation critical exponents. For an infinite system, the critical threshold corresponds to the first point (as p increases) where the size of the clusters become infinite.
In the systems described so far, it has been assumed that the occupation of a site or bond is completely random—this is the so-called Bernoulli percolation. For a continuum system, random occupancy corresponds to the points being placed by a Poisson process. Further variations involve correlated percolation, such as percolation clusters related to Ising and Potts models of ferromagnets, in which the bonds are put down by the Fortuin–Kasteleyn method. [2] In bootstrap or k-sat percolation, sites and/or bonds are first occupied and then successively culled from a system if a site does not have at least k neighbors. Another important model of percolation, in a different universality class altogether, is directed percolation, where connectivity along a bond depends upon the direction of the flow. Another variation of recent interest is Explosive Percolation, whose thresholds are listed on that page.
Over the last several decades, a tremendous amount of work has gone into finding exact and approximate values of the percolation thresholds for a variety of these systems. Exact thresholds are only known for certain two-dimensional lattices that can be broken up into a self-dual array, such that under a triangle-triangle transformation, the system remains the same. Studies using numerical methods have led to numerous improvements in algorithms and several theoretical discoveries.
Simple duality in two dimensions implies that all fully triangulated lattices (e.g., the triangular, union jack, cross dual, martini dual and asanoha or 3-12 dual, and the Delaunay triangulation) all have site thresholds of 1⁄2, and self-dual lattices (square, martini-B) have bond thresholds of 1⁄2.
The notation such as (4,82) comes from Grünbaum and Shephard, [3] and indicates that around a given vertex, going in the clockwise direction, one encounters first a square and then two octagons. Besides the eleven Archimedean lattices composed of regular polygons with every site equivalent, many other more complicated lattices with sites of different classes have been studied.
Error bars in the last digit or digits are shown by numbers in parentheses. Thus, 0.729724(3) signifies 0.729724 ± 0.000003, and 0.74042195(80) signifies 0.74042195 ± 0.00000080. The error bars variously represent one or two standard deviations in net error (including statistical and expected systematic error), or an empirical confidence interval, depending upon the source.
For a random tree-like network (i.e., a connected network with no cycle) without degree-degree correlation, it can be shown that such network can have a giant component, and the percolation threshold (transmission probability) is given by
.
Where is the generating function corresponding to the excess degree distribution, is the average degree of the network and is the second moment of the degree distribution. So, for example, for an ER network, since the degree distribution is a Poisson distribution, the threshold is at .
In networks with low clustering, , the critical point gets scaled by such that: [4]
This indicates that for a given degree distribution, the clustering leads to a larger percolation threshold, mainly because for a fixed number of links, the clustering structure reinforces the core of the network with the price of diluting the global connections. For networks with high clustering, strong clustering could induce the core–periphery structure, in which the core and periphery might percolate at different critical points, and the above approximate treatment is not applicable. [5]
Lattice | z | Site percolation threshold | Bond percolation threshold | |
---|---|---|---|---|
3-12 or super-kagome, (3, 122 ) | 3 | 3 | 0.807900764... = (1 − 2 sin (π/18))1⁄2 [7] | 0.74042195(80), [8] 0.74042077(2), [9] 0.740420800(2), [10] 0.7404207988509(8), [11] [12] 0.740420798850811610(2), [13] |
cross, truncated trihexagonal (4, 6, 12) | 3 | 3 | 0.746, [14] 0.750, [15] 0.747806(4), [7] 0.7478008(2) [11] | 0.6937314(1), [11] 0.69373383(72), [8] 0.693733124922(2) [13] |
square octagon, bathroom tile, 4-8, truncated square (4, 82) | 3 | - | 0.729, [14] 0.729724(3), [7] 0.7297232(5) [11] | 0.6768, [16] 0.67680232(63), [8] 0.6768031269(6), [11] 0.6768031243900113(3), [13] |
honeycomb (63) | 3 | 3 | 0.6962(6), [17] 0.697040230(5), [11] 0.6970402(1), [18] 0.6970413(10), [19] 0.697043(3), [7] | 0.652703645... = 1-2 sin (π/18), 1+ p3-3p2=0 [20] |
kagome (3, 6, 3, 6) | 4 | 4 | 0.652703645... = 1 − 2 sin(π/18) [20] | 0.5244053(3), [21] 0.52440516(10), [19] 0.52440499(2), [18] 0.524404978(5), [9] 0.52440572..., [22] 0.52440500(1), [10] 0.524404999173(3), [11] [12] 0.524404999167439(4) [23] 0.52440499916744820(1) [13] |
ruby, [24] rhombitrihexagonal (3, 4, 6, 4) | 4 | 4 | 0.620, [14] 0.621819(3), [7] 0.62181207(7) [11] | 0.52483258(53), [8] 0.5248311(1), [11] 0.524831461573(1) [13] |
square (44) | 4 | 4 | 0.59274(10), [25] 0.59274605079210(2), [23] 0.59274601(2), [11] 0.59274605095(15), [26] 0.59274621(13), [27] 0.592746050786(3), [28] 0.59274621(33), [29] 0.59274598(4), [30] [31] 0.59274605(3), [18] 0.593(1), [32] 0.591(1), [33] 0.569(13), [34] 0.59274(5) [35] | 1⁄2 |
snub hexagonal, maple leaf [36] (34,6) | 5 | 5 | 0.579 [15] 0.579498(3) [7] | 0.43430621(50), [8] 0.43432764(3), [11] 0.4343283172240(6), [13] |
snub square, puzzle (32, 4, 3, 4 ) | 5 | 5 | 0.550, [14] [37] 0.550806(3) [7] | 0.41413743(46), [8] 0.4141378476(7), [11] 0.4141378565917(1), [13] |
frieze, elongated triangular(33, 42) | 5 | 5 | 0.549, [14] 0.550213(3), [7] 0.5502(8) [38] | 0.4196(6), [38] 0.41964191(43), [8] 0.41964044(1), [11] 0.41964035886369(2) [13] |
triangular (36) | 6 | 6 | 1⁄2 | 0.347296355... = 2 sin (π/18), 1 + p3 − 3p = 0 [20] |
Note: sometimes "hexagonal" is used in place of honeycomb, although in some contexts a triangular lattice is also called a hexagonal lattice. z = bulk coordination number.
In this section, sq-1,2,3 corresponds to square (NN+2NN+3NN), [39] etc. Equivalent to square-2N+3N+4N, [40] sq(1,2,3). [41] tri = triangular, hc = honeycomb.
Lattice | z | Site percolation threshold | Bond percolation threshold |
---|---|---|---|
sq-1, sq-2, sq-3, sq-5 | 4 | 0.5927... [39] [40] (square site) | |
sq-1,2, sq-2,3, sq-3,5 | 8 | 0.407... [39] [40] [42] (square matching) | 0.25036834(6), [18] 0.2503685, [43] 0.25036840(4) [44] |
sq-1,3 | 8 | 0.337 [39] [40] | 0.2214995 [43] |
sq-2,5: 2NN+5NN | 8 | 0.337 [40] | |
hc-1,2,3: honeycomb-NN+2NN+3NN | 12 | 0.300, [41] 0.300, [15] 0.302960... = 1-pc(site, hc) [45] | |
tri-1,2: triangular-NN+2NN | 12 | 0.295, [41] 0.289, [15] 0.290258(19) [46] | |
tri-2,3: triangular-2NN+3NN | 12 | 0.232020(36), [47] 0.232020(20) [46] | |
sq-4: square-4NN | 8 | 0.270... [40] | |
sq-1,5: square-NN+5NN (r ≤ 2) | 8 | 0.277 [40] | |
sq-1,2,3: square-NN+2NN+3NN | 12 | 0.292, [48] 0.290(5) [49] 0.289, [15] 0.288, [39] [40] | 0.1522203 [43] |
sq-2,3,5: square-2NN+3NN+5NN | 12 | 0.288 [40] | |
sq-1,4: square-NN+4NN | 12 | 0.236 [40] | |
sq-2,4: square-2NN+4NN | 12 | 0.225 [40] | |
tri-4: triangular-4NN | 12 | 0.192450(36), [47] 0.1924428(50) [46] | |
hc-2,4: honeycomb-2NN+4NN | 12 | 0.2374 [50] | |
tri-1,3: triangular-NN+3NN | 12 | 0.264539(21) [46] | |
tri-1,2,3: triangular-NN+2NN+3NN | 18 | 0.225, [48] 0.215, [15] 0.215459(36) [47] 0.2154657(17) [46] | |
sq-3,4: 3NN+4NN | 12 | 0.221 [40] | |
sq-1,2,5: NN+2NN+5NN | 12 | 0.240 [40] | 0.13805374 [43] |
sq-1,3,5: NN+3NN+5NN | 12 | 0.233 [40] | |
sq-4,5: 4NN+5NN | 12 | 0.199 [40] | |
sq-1,2,4: NN+2NN+4NN | 16 | 0.219 [40] | |
sq-1,3,4: NN+3NN+4NN | 16 | 0.208 [40] | |
sq-2,3,4: 2NN+3NN+4NN | 16 | 0.202 [40] | |
sq-1,4,5: NN+4NN+5NN | 16 | 0.187 [40] | |
sq-2,4,5: 2NN+4NN+5NN | 16 | 0.182 [40] | |
sq-3,4,5: 3NN+4NN+5NN | 16 | 0.179 [40] | |
sq-1,2,3,5: NN+2NN+3NN+5NN | 16 | 0.208 [40] | 0.1032177 [43] |
tri-4,5: 4NN+5NN | 18 | 0.140250(36), [47] | |
sq-1,2,3,4: NN+2NN+3NN+4NN () | 20 | 0.19671(9), [51] 0.196, [40] 0.196724(10) [52] | 0.0841509 [43] |
sq-1,2,4,5: NN+2NN+4NN+5NN | 20 | 0.177 [40] | |
sq-1,3,4,5: NN+3NN+4NN+5NN | 20 | 0.172 [40] | |
sq-2,3,4,5: 2NN+3NN+4NN+5NN | 20 | 0.167 [40] | |
sq-1,2,3,5,6: NN+2NN+3NN+5NN+6NN | 20 | 0.0783110 [43] | |
sq-1,2,3,4,5: NN+2NN+3NN+4NN+5NN () | 24 | 0.164 [40] | |
tri-1,4,5: NN+4NN+5NN | 24 | 0.131660(36) [47] | |
sq-1,...,6: NN+...+6NN (r≤3) | 28 | 0.142 [15] | 0.0558493 [43] |
tri-2,3,4,5: 2NN+3NN+4NN+5NN | 30 | 0.117460(36) [47] 0.135823(27) [46] | |
tri-1,2,3,4,5: NN+2NN+3NN+4NN+5NN | 36 | 0.115, [15] 0.115740(36), [47] 0.1157399(58) [46] | |
sq-1,...,7: NN+...+7NN () | 36 | 0.113 [15] | 0.04169608 [43] |
square: square distance ≤ 4 | 40 | 0.105(5) [49] | |
sq-(1,...,8: NN+..+8NN () | 44 | 0.095, [37] 0.095765(5), [52] 0.09580(2) [51] | |
sq-1,...,9: NN+..+9NN (r≤4) | 48 | 0.086 [15] | 0.02974268 [43] |
sq-1,...,11: NN+...+11NN () | 60 | 0.02301190(3) [43] | |
sq-1,...,23 (r ≤ 7) | 148 | 0.008342595 [44] | |
sq-1,...,32: NN+...+32NN () | 224 | 0.0053050415(33) [43] | |
sq-1,...,86: NN+...+86NN (r≤15) | 708 | 0.001557644(4) [53] | |
sq-1,...,141: NN+...+141NN () | 1224 | 0.000880188(90) [43] | |
sq-1,...,185: NN+...+185NN (r≤23) | 1652 | 0.000645458(4) [53] | |
sq-1,...,317: NN+...+317NN (r≤31) | 3000 | 0.000349601(3) [53] | |
sq-1,...,413: NN+...+413NN () | 4016 | 0.0002594722(11) [43] | |
square: square distance ≤ 6 | 84 | 0.049(5) [49] | |
square: square distance ≤ 8 | 144 | 0.028(5) [49] | |
square: square distance ≤ 10 | 220 | 0.019(5) [49] | |
2x2 lattice squares* (also above) | 20 | φc = 0.58365(2), [52] pc = 0.196724(10), [52] 0.19671(9), [51] | |
3x3 lattice squares* (also above) | 44 | φc = 0.59586(2), [52] pc = 0.095765(5), [52] 0.09580(2) [51] | |
4x4 lattice squares* | 76 | φc = 0.60648(1), [52] pc = 0.0566227(15), [52] 0.05665(3), [51] | |
5x5 lattice squares* | 116 | φc = 0.61467(2), [52] pc = 0.037428(2), [52] 0.03745(2), [51] | |
6x6 lattice squares* | 220 | pc = 0.02663(1), [51] | |
10x10 lattice squares* | 436 | φc = 0.36391(2), [52] pc = 0.0100576(5) [52] | |
Here NN = nearest neighbor, 2NN = second nearest neighbor (or next nearest neighbor), 3NN = third nearest neighbor (or next-next nearest neighbor), etc. These are also called 2N, 3N, 4N respectively in some papers. [39]
Here, one distorts a regular lattice of unit spacing by moving vertices uniformly within the box , and considers percolation when sites are within Euclidean distance of each other.
Lattice | Site percolation threshold | Bond percolation threshold | |||
---|---|---|---|---|---|
square | 0.2 | 1.1 | 0.8025(2) [54] | ||
0.2 | 1.2 | 0.6667(5) [54] | |||
0.1 | 1.1 | 0.6619(1) [54] | |||
Site threshold is number of overlapping objects per lattice site. k is the length (net area). Overlapping squares are shown in the complex neighborhood section. Here z is the coordination number to k-mers of either orientation, with for sticks.
System | k | z | Site coverage φc | Site percolation threshold pc |
---|---|---|---|---|
1 x 2 dimer, square lattice | 2 | 22 | 0.54691 [51] 0.5483(2) [55] | 0.17956(3) [51] 0.18019(9) [55] |
1 x 2 aligned dimer, square lattice | 2 | 14 | 0.5715(18) [55] | 0.3454(13) [55] |
1 x 3 trimer, square lattice | 3 | 37 | 0.49898 [51] 0.50004(64) [55] | 0.10880(2) [51] 0.1093(2) [55] |
1 x 4 stick, square lattice | 4 | 54 | 0.45761 [51] | 0.07362(2) [51] |
1 x 5 stick, square lattice | 5 | 73 | 0.42241 [51] | 0.05341(1) [51] |
1 x 6 stick, square lattice | 6 | 94 | 0.39219 [51] | 0.04063(2) [51] |
The coverage is calculated from by for sticks, because there are sites where a stick will cause an overlap with a given site.
For aligned sticks:
Lattice | z | Site percolation threshold | Bond percolation threshold |
---|---|---|---|
(3, 122 ) | 3 | ||
(4, 6, 12) | 3 | ||
(4, 82) | 3 | 0.676835..., 4p3 + 3p4 − 6 p5 − 2 p6 = 1 [56] | |
honeycomb (63) | 3 | ||
kagome (3, 6, 3, 6) | 4 | 0.524430..., 3p2 + 6p3 − 12 p4+ 6 p5 − p6 = 1 [57] | |
(3, 4, 6, 4) | 4 | ||
square (44) | 4 | 1⁄2 (exact) | |
(34,6 ) | 5 | 0.434371..., 12p3 + 36p4 − 21p5 − 327 p6 + 69p7 + 2532p8 − 6533 p9 + 8256 p10 − 6255p11 + 2951p12 − 837 p13 + 126 p14 − 7p15 = 1 [ citation needed ] | |
snub square, puzzle (32, 4, 3, 4 ) | 5 | ||
(33, 42) | 5 | ||
triangular (36) | 6 | 1⁄2 (exact) | |
In AB percolation, a is the proportion of A sites among B sites, and bonds are drawn between sites of opposite species. [58] It is also called antipercolation.
In colored percolation, occupied sites are assigned one of colors with equal probability, and connection is made along bonds between neighbors of different colors. [59]
Lattice | z | Site percolation threshold | |
---|---|---|---|
triangular AB | 6 | 6 | 0.2145, [58] 0.21524(34), [60] 0.21564(3) [61] |
AB on square-covering lattice | 6 | 6 | [62] |
square three-color | 4 | 4 | 0.80745(5) [59] |
square four-color | 4 | 4 | 0.73415(4) [59] |
square five-color | 4 | 4 | 0.69864(7) [59] |
square six-color | 4 | 4 | 0.67751(5) [59] |
triangular two-color | 6 | 6 | 0.72890(4) [59] |
triangular three-color | 6 | 6 | 0.63005(4) [59] |
triangular four-color | 6 | 6 | 0.59092(3) [59] |
triangular five-color | 6 | 6 | 0.56991(5) [59] |
triangular six-color | 6 | 6 | 0.55679(5) [59] |
Site bond percolation. Here is the site occupation probability and is the bond occupation probability, and connectivity is made only if both the sites and bonds along a path are occupied. The criticality condition becomes a curve = 0, and some specific critical pairs are listed below.
Square lattice:
Lattice | z | Site percolation threshold | Bond percolation threshold | |
---|---|---|---|---|
square | 4 | 4 | 0.615185(15) [63] | 0.95 |
0.667280(15) [63] | 0.85 | |||
0.732100(15) [63] | 0.75 | |||
0.75 | 0.726195(15) [63] | |||
0.815560(15) [63] | 0.65 | |||
0.85 | 0.615810(30) [63] | |||
0.95 | 0.533620(15) [63] |
Honeycomb (hexagonal) lattice:
Lattice | z | Site percolation threshold | Bond percolation threshold | |
---|---|---|---|---|
honeycomb | 3 | 3 | 0.7275(5) [64] | 0.95 |
0. 0.7610(5) [64] | 0.90 | |||
0.7986(5) [64] | 0.85 | |||
0.80 | 0.8481(5) [64] | |||
0.8401(5) [64] | 0.80 | |||
0.85 | 0.7890(5) [64] | |||
0.90 | 0.7377(5) [64] | |||
0.95 | 0.6926(5) [64] |
Kagome lattice:
Lattice | z | Site percolation threshold | Bond percolation threshold | |
---|---|---|---|---|
kagome | 4 | 4 | 0.6711(4), [64] 0.67097(3) [65] | 0.95 |
0.6914(5), [64] 0.69210(2) [65] | 0.90 | |||
0.7162(5), [64] 0.71626(3) [65] | 0.85 | |||
0.7428(5), [64] 0.74339(3) [65] | 0.80 | |||
0.75 | 0.7894(9) [64] | |||
0.7757(8), [64] 0.77556(3) [65] | 0.75 | |||
0.80 | 0.7152(7) [64] | |||
0.81206(3) [65] | 0.70 | |||
0.85 | 0.6556(6) [64] | |||
0.85519(3) [65] | 0.65 | |||
0.90 | 0.6046(5) [64] | |||
0.90546(3) [65] | 0.60 | |||
0.95 | 0.5615(4) [64] | |||
0.96604(4) [65] | 0.55 | |||
0.9854(3) [65] | 0.53 |
* For values on different lattices, see "An investigation of site-bond percolation on many lattices". [64]
Approximate formula for site-bond percolation on a honeycomb lattice
Lattice | z | Threshold | Notes | |
---|---|---|---|---|
(63) honeycomb | 3 | 3 | , When equal: ps = pb = 0.82199 | approximate formula, ps = site prob., pb = bond prob., pbc = 1 − 2 sin (π/18), [19] exact at ps=1, pb=pbc. |
Laves lattices are the duals to the Archimedean lattices. Drawings from. [6] See also Uniform tilings.
Lattice | z | Site percolation threshold | Bond percolation threshold | |
---|---|---|---|---|
Cairo pentagonal D(32,4,3,4)=(2⁄3)(53)+(1⁄3)(54) | 3,4 | 3 1⁄3 | 0.6501834(2), [11] 0.650184(5) [6] | 0.585863... = 1 − pcbond(32,4,3,4) |
Pentagonal D(33,42)=(1⁄3)(54)+(2⁄3)(53) | 3,4 | 3 1⁄3 | 0.6470471(2), [11] 0.647084(5), [6] 0.6471(6) [38] | 0.580358... = 1 − pcbond(33,42), 0.5800(6) [38] |
D(34,6)=(1⁄5)(46)+(4⁄5)(43) | 3,6 | 3 3⁄5 | 0.639447 [6] | 0.565694... = 1 − pcbond(34,6 ) |
dice, rhombille tiling D(3,6,3,6) = (1⁄3)(46) + (2⁄3)(43) | 3,6 | 4 | 0.5851(4), [66] 0.585040(5) [6] | 0.475595... = 1 − pcbond(3,6,3,6 ) |
ruby dual D(3,4,6,4) = (1⁄6)(46) + (2⁄6)(43) + (3⁄6)(44) | 3,4,6 | 4 | 0.582410(5) [6] | 0.475167... = 1 − pcbond(3,4,6,4 ) |
union jack, tetrakis square tiling D(4,82) = (1⁄2)(34) + (1⁄2)(38) | 4,8 | 6 | 1⁄2 | 0.323197... = 1 − pcbond(4,82 ) |
bisected hexagon, [67] cross dual D(4,6,12)= (1⁄6)(312)+(2⁄6)(36)+(1⁄2)(34) | 4,6,12 | 6 | 1⁄2 | 0.306266... = 1 − pcbond(4,6,12) |
asanoha (hemp leaf) [68] D(3, 122)=(2⁄3)(33)+(1⁄3)(312) | 3,12 | 6 | 1⁄2 | 0.259579... = 1 − pcbond(3, 122) |
Top 3 lattices: #13 #12 #36
Bottom 3 lattices: #34 #37 #11
Top 2 lattices: #35 #30
Bottom 2 lattices: #41 #42
Top 4 lattices: #22 #23 #21 #20
Bottom 3 lattices: #16 #17 #15
Top 2 lattices: #31 #32
Bottom lattice: #33
# | Lattice | z | Site percolation threshold | Bond percolation threshold | |
---|---|---|---|---|---|
41 | (1⁄2)(3,4,3,12) + (1⁄2)(3, 122) | 4,3 | 3.5 | 0.7680(2) [69] | 0.67493252(36)[ citation needed ] |
42 | (1⁄3)(3,4,6,4) + (2⁄3)(4,6,12) | 4,3 | 31⁄3 | 0.7157(2) [69] | 0.64536587(40)[ citation needed ] |
36 | (1⁄7)(36) + (6⁄7)(32,4,12) | 6,4 | 4 2⁄7 | 0.6808(2) [69] | 0.55778329(40)[ citation needed ] |
15 | (2⁄3)(32,62) + (1⁄3)(3,6,3,6) | 4,4 | 4 | 0.6499(2) [69] | 0.53632487(40)[ citation needed ] |
34 | (1⁄7)(36) + (6⁄7)(32,62) | 6,4 | 4 2⁄7 | 0.6329(2) [69] | 0.51707873(70)[ citation needed ] |
16 | (4⁄5)(3,42,6) + (1⁄5)(3,6,3,6) | 4,4 | 4 | 0.6286(2) [69] | 0.51891529(35)[ citation needed ] |
17 | (4⁄5)(3,42,6) + (1⁄5)(3,6,3,6)* | 4,4 | 4 | 0.6279(2) [69] | 0.51769462(35)[ citation needed ] |
35 | (2⁄3)(3,42,6) + (1⁄3)(3,4,6,4) | 4,4 | 4 | 0.6221(2) [69] | 0.51973831(40)[ citation needed ] |
11 | (1⁄2)(34,6) + (1⁄2)(32,62) | 5,4 | 4.5 | 0.6171(2) [69] | 0.48921280(37)[ citation needed ] |
37 | (1⁄2)(33,42) + (1⁄2)(3,4,6,4) | 5,4 | 4.5 | 0.5885(2) [69] | 0.47229486(38)[ citation needed ] |
30 | (1⁄2)(32,4,3,4) + (1⁄2)(3,4,6,4) | 5,4 | 4.5 | 0.5883(2) [69] | 0.46573078(72)[ citation needed ] |
23 | (1⁄2)(33,42) + (1⁄2)(44) | 5,4 | 4.5 | 0.5720(2) [69] | 0.45844622(40)[ citation needed ] |
22 | (2⁄3)(33,42) + (1⁄3)(44) | 5,4 | 4 2⁄3 | 0.5648(2) [69] | 0.44528611(40)[ citation needed ] |
12 | (1⁄4)(36) + (3⁄4)(34,6) | 6,5 | 5 1⁄4 | 0.5607(2) [69] | 0.41109890(37)[ citation needed ] |
33 | (1⁄2)(33,42) + (1⁄2)(32,4,3,4) | 5,5 | 5 | 0.5505(2) [69] | 0.41628021(35)[ citation needed ] |
32 | (1⁄3)(33,42) + (2⁄3)(32,4,3,4) | 5,5 | 5 | 0.5504(2) [69] | 0.41549285(36)[ citation needed ] |
31 | (1⁄7)(36) + (6⁄7)(32,4,3,4) | 6,5 | 5 1⁄7 | 0.5440(2) [69] | 0.40379585(40)[ citation needed ] |
13 | (1⁄2)(36) + (1⁄2)(34,6) | 6,5 | 5.5 | 0.5407(2) [69] | 0.38914898(35)[ citation needed ] |
21 | (1⁄3)(36) + (2⁄3)(33,42) | 6,5 | 5 1⁄3 | 0.5342(2) [69] | 0.39491996(40)[ citation needed ] |
20 | (1⁄2)(36) + (1⁄2)(33,42) | 6,5 | 5.5 | 0.5258(2) [69] | 0.38285085(38)[ citation needed ] |
This figure shows something similar to the 2-uniform lattice #37, except the polygons are not all regular—there is a rectangle in the place of the two squares—and the size of the polygons is changed. This lattice is in the isoradial representation in which each polygon is inscribed in a circle of unit radius. The two squares in the 2-uniform lattice must now be represented as a single rectangle in order to satisfy the isoradial condition. The lattice is shown by black edges, and the dual lattice by red dashed lines. The green circles show the isoradial constraint on both the original and dual lattices. The yellow polygons highlight the three types of polygons on the lattice, and the pink polygons highlight the two types of polygons on the dual lattice. The lattice has vertex types (1⁄2)(33,42) + (1⁄2)(3,4,6,4), while the dual lattice has vertex types (1⁄15)(46)+(6⁄15)(42,52)+(2⁄15)(53)+(6⁄15)(52,4). The critical point is where the longer bonds (on both the lattice and dual lattice) have occupation probability p = 2 sin (π/18) = 0.347296... which is the bond percolation threshold on a triangular lattice, and the shorter bonds have occupation probability 1 − 2 sin(π/18) = 0.652703..., which is the bond percolation on a hexagonal lattice. These results follow from the isoradial condition [70] but also follow from applying the star-triangle transformation to certain stars on the honeycomb lattice. Finally, it can be generalized to having three different probabilities in the three different directions, p1, p2 and p3 for the long bonds, and 1 − p1, 1 − p2, and 1 − p3 for the short bonds, where p1, p2 and p3 satisfy the critical surface for the inhomogeneous triangular lattice.
To the left, center, and right are: the martini lattice, the martini-A lattice, the martini-B lattice. Below: the martini covering/medial lattice, same as the 2×2, 1×1 subnet for kagome-type lattices (removed).
Some other examples of generalized bow-tie lattices (a-d) and the duals of the lattices (e-h):
Lattice | z | Site percolation threshold | Bond percolation threshold | |
---|---|---|---|---|
martini (3⁄4)(3,92)+(1⁄4)(93) | 3 | 3 | 0.764826..., 1 + p4 − 3p3 = 0 [71] | 0.707107... = 1/√2 [72] |
bow-tie (c) | 3,4 | 3 1⁄7 | 0.672929..., 1 − 2p3 − 2p4 − 2p5 − 7p6 + 18p7 + 11p8 − 35p9 + 21p10 − 4p11 = 0 [73] | |
bow-tie (d) | 3,4 | 3 1⁄3 | 0.625457..., 1 − 2p2 − 3p3 + 4p4 − p5 = 0 [73] | |
martini-A (2⁄3)(3,72)+(1⁄3)(3,73) | 3,4 | 3 1⁄3 | 1/√2 [73] | 0.625457..., 1 − 2p2 − 3p3 + 4p4 − p5 = 0 [73] |
bow-tie dual (e) | 3,4 | 3 2⁄3 | 0.595482..., 1-pcbond (bow-tie (a)) [73] | |
bow-tie (b) | 3,4,6 | 3 2⁄3 | 0.533213..., 1 − p − 2p3 -4p4-4p5+156+ 13p7-36p8+19p9+ p10 + p11=0 [73] | |
martini covering/medial (1⁄2)(33,9) + (1⁄2)(3,9,3,9) | 4 | 4 | 0.707107... = 1/√2 [72] | 0.57086651(33)[ citation needed ] |
martini-B (1⁄2)(3,5,3,52) + (1⁄2)(3,52) | 3, 5 | 4 | 0.618034... = 2/(1 + √5), 1- p2 − p = 0 [71] [73] | 1⁄2 [72] [73] |
bow-tie dual (f) | 3,4,8 | 4 2⁄5 | 0.466787..., 1 − pcbond (bow-tie (b)) [73] | |
bow-tie (a) (1⁄2)(32,4,32,4) + (1⁄2)(3,4,3) | 4,6 | 5 | 0.5472(2), [38] 0.5479148(7) [74] | 0.404518..., 1 − p − 6p2 + 6p3 − p5 = 0 [73] [75] |
bow-tie dual (h) | 3,6,8 | 5 | 0.374543..., 1 − pcbond(bow-tie (d)) [73] | |
bow-tie dual (g) | 3,6,10 | 5 1⁄2 | 0.547... = pcsite(bow-tie(a)) | 0.327071..., 1 − pcbond(bow-tie (c)) [73] |
martini dual (1⁄2)(33) + (1⁄2)(39) | 3,9 | 6 | 1⁄2 | 0.292893... = 1 − 1/√2 [72] |
Lattice | z | Site percolation threshold | Bond percolation threshold | |
---|---|---|---|---|
(4, 6, 12) covering/medial | 4 | 4 | pcbond(4, 6, 12) = 0.693731... | 0.5593140(2), [11] 0.559315(1)[ citation needed ] |
(4, 82) covering/medial, square kagome | 4 | 4 | pcbond(4,82) = 0.676803... | 0.544798017(4), [11] 0.54479793(34)[ citation needed ] |
(34, 6) medial | 4 | 4 | 0.5247495(5) [11] | |
(3,4,6,4) medial | 4 | 4 | 0.51276 [11] | |
(32, 4, 3, 4) medial | 4 | 4 | 0.512682929(8) [11] | |
(33, 42) medial | 4 | 4 | 0.5125245984(9) [11] | |
square covering (non-planar) | 6 | 6 | 1⁄2 | 0.3371(1) [56] |
square matching lattice (non-planar) | 8 | 8 | 1 − pcsite(square) = 0.407253... | 0.25036834(6) [18] |
Lattice | z | Site percolation threshold | Bond percolation threshold | |
---|---|---|---|---|
K(2,2) | 4 | 4 | 0.51253(14) [78] | 0.44778(15) [78] |
K(3,3) | 6 | 6 | 0.43760(15) [78] | 0.35502(15) [78] |
K(4,4) | 8 | 8 | 0.38675(7) [78] | 0.29427(12) [78] |
K(5,5) | 10 | 10 | 0.35115(13) [78] | 0.25159(13) [78] |
K(6,6) | 12 | 12 | 0.32232(13) [78] | 0.21942(11) [78] |
K(7,7) | 14 | 14 | 0.30052(14) [78] | 0.19475(9) [78] |
K(8,8) | 16 | 16 | 0.28103(11) [78] | 0.17496(10) [78] |
The 2 x 2, 3 x 3, and 4 x 4 subnet kagome lattices. The 2 × 2 subnet is also known as the "triangular kagome" lattice. [79]
Lattice | z | Site percolation threshold | Bond percolation threshold | |
---|---|---|---|---|
checkerboard – 2 × 2 subnet | 4,3 | 0.596303(1) [80] | ||
checkerboard – 4 × 4 subnet | 4,3 | 0.633685(9) [80] | ||
checkerboard – 8 × 8 subnet | 4,3 | 0.642318(5) [80] | ||
checkerboard – 16 × 16 subnet | 4,3 | 0.64237(1) [80] | ||
checkerboard – 32 × 32 subnet | 4,3 | 0.64219(2) [80] | ||
checkerboard – subnet | 4,3 | 0.642216(10) [80] | ||
kagome – 2 × 2 subnet = (3, 122) covering/medial | 4 | pcbond (3, 122) = 0.74042077... | 0.600861966960(2), [11] 0.6008624(10), [19] 0.60086193(3) [9] | |
kagome – 3 × 3 subnet | 4 | 0.6193296(10), [19] 0.61933176(5), [9] 0.61933044(32)[ citation needed ] | ||
kagome – 4 × 4 subnet | 4 | 0.625365(3), [19] 0.62536424(7) [9] | ||
kagome – subnet | 4 | 0.628961(2) [19] | ||
kagome – (1 × 1):(2 × 2) subnet = martini covering/medial | 4 | pcbond(martini) = 1/√2 = 0.707107... | 0.57086648(36)[ citation needed ] | |
kagome – (1 × 1):(3 × 3) subnet | 4,3 | 0.728355596425196... [9] | 0.58609776(37)[ citation needed ] | |
kagome – (1 × 1):(4 × 4) subnet | 0.738348473943256... [9] | |||
kagome – (1 × 1):(5 × 5) subnet | 0.743548682503071... [9] | |||
kagome – (1 × 1):(6 × 6) subnet | 0.746418147634282... [9] | |||
kagome – (2 × 2):(3 × 3) subnet | 0.61091770(30)[ citation needed ] | |||
triangular – 2 × 2 subnet | 6,4 | 0.471628788 [80] | ||
triangular – 3 × 3 subnet | 6,4 | 0.509077793 [80] | ||
triangular – 4 × 4 subnet | 6,4 | 0.524364822 [80] | ||
triangular – 5 × 5 subnet | 6,4 | 0.5315976(10) [80] | ||
triangular – subnet | 6,4 | 0.53993(1) [80] |
(For more results and comparison to the jamming density, see Random sequential adsorption)
system | z | Site threshold |
---|---|---|
dimers on a honeycomb lattice | 3 | 0.69, [81] 0.6653 [82] |
dimers on a triangular lattice | 6 | 0.4872(8), [81] 0.4873, [82] |
aligned linear dimers on a triangular lattice | 6 | 0.5157(2) [83] |
aligned linear 4-mers on a triangular lattice | 6 | 0.5220(2) [83] |
aligned linear 8-mers on a triangular lattice | 6 | 0.5281(5) [83] |
aligned linear 12-mers on a triangular lattice | 6 | 0.5298(8) [83] |
linear 16-mers on a triangular lattice | 6 | aligned 0.5328(7) [83] |
linear 32-mers on a triangular lattice | 6 | aligned 0.5407(6) [83] |
linear 64-mers on a triangular lattice | 6 | aligned 0.5455(4) [83] |
aligned linear 80-mers on a triangular lattice | 6 | 0.5500(6) [83] |
aligned linear k on a triangular lattice | 6 | 0.582(9) [83] |
dimers and 5% impurities, triangular lattice | 6 | 0.4832(7) [84] |
parallel dimers on a square lattice | 4 | 0.5863 [85] |
dimers on a square lattice | 4 | 0.5617, [85] 0.5618(1), [86] 0.562, [87] 0.5713 [82] |
linear 3-mers on a square lattice | 4 | 0.528 [87] |
3-site 120° angle, 5% impurities, triangular lattice | 6 | 0.4574(9) [84] |
3-site triangles, 5% impurities, triangular lattice | 6 | 0.5222(9) [84] |
linear trimers and 5% impurities, triangular lattice | 6 | 0.4603(8) [84] |
linear 4-mers on a square lattice | 4 | 0.504 [87] |
linear 5-mers on a square lattice | 4 | 0.490 [87] |
linear 6-mers on a square lattice | 4 | 0.479 [87] |
linear 8-mers on a square lattice | 4 | 0.474, [87] 0.4697(1) [86] |
linear 10-mers on a square lattice | 4 | 0.469 [87] |
linear 16-mers on a square lattice | 4 | 0.4639(1) [86] |
linear 32-mers on a square lattice | 4 | 0.4747(2) [86] |
The threshold gives the fraction of sites occupied by the objects when site percolation first takes place (not at full jamming). For longer k-mers see Ref. [88]
Here, we are dealing with networks that are obtained by covering a lattice with dimers, and then consider bond percolation on the remaining bonds. In discrete mathematics, this problem is known as the 'perfect matching' or the 'dimer covering' problem.
system | z | Bond threshold |
---|---|---|
Parallel covering, square lattice | 6 | 0.381966... [89] |
Shifted covering, square lattice | 6 | 0.347296... [89] |
Staggered covering, square lattice | 6 | 0.376825(2) [89] |
Random covering, square lattice | 6 | 0.367713(2) [89] |
Parallel covering, triangular lattice | 10 | 0.237418... [89] |
Staggered covering, triangular lattice | 10 | 0.237497(2) [89] |
Random covering, triangular lattice | 10 | 0.235340(1) [89] |
System is composed of ordinary (non-avoiding) random walks of length l on the square lattice. [90]
l (polymer length) | z | Bond percolation |
---|---|---|
1 | 4 | 0.5(exact) [91] |
2 | 4 | 0.47697(4) [91] |
4 | 4 | 0.44892(6) [91] |
8 | 4 | 0.41880(4) [91] |
k | z | Site thresholds | Bond thresholds |
---|---|---|---|
1 | 4 | 0.593(2) [92] | 0.5009(2) [92] |
2 | 4 | 0.564(2) [92] | 0.4859(2) [92] |
3 | 4 | 0.552(2) [92] | 0.4732(2) [92] |
4 | 4 | 0.542(2) [92] | 0.4630(2) [92] |
5 | 4 | 0.531(2) [92] | 0.4565(2) [92] |
6 | 4 | 0.522(2) [92] | 0.4497(2) [92] |
7 | 4 | 0.511(2) [92] | 0.4423(2) [92] |
8 | 4 | 0.502(2) [92] | 0.4348(2) [92] |
9 | 4 | 0.493(2) [92] | 0.4291(2) [92] |
10 | 4 | 0.488(2) [92] | 0.4232(2) [92] |
11 | 4 | 0.482(2) [92] | 0.4159(2) [92] |
12 | 4 | 0.476(2) [92] | 0.4114(2) [92] |
13 | 4 | 0.471(2) [92] | 0.4061(2) [92] |
14 | 4 | 0.467(2) [92] | 0.4011(2) [92] |
15 | 4 | 0.4011(2) [92] | 0.3979(2) [92] |
Lattice | z | Site percolation threshold | Bond percolation threshold |
---|---|---|---|
bow-tie with p = 1⁄2 on one non-diagonal bond | 3 | 0.3819654(5), [93] [56] | |
System | Φc | ηc | nc |
---|---|---|---|
Disks of radius r | 0.67634831(2), [94] 0.6763475(6), [95] 0.676339(4), [96] 0.6764(4), [97] 0.6766(5), [98] 0.676(2), [99] 0.679, [100] 0.674 [101] 0.676, [102] 0.680 [103] | 1.1280867(5), [104] 1.1276(9), [105] 1.12808737(6), [94] 1.128085(2), [95] 1.128059(12), [96] 1.13,[ citation needed ] 0.8 [106] | 1.43632505(10), [107] 1.43632545(8), [94] 1.436322(2), [95] 1.436289(16), [96] 1.436320(4), [108] 1.436323(3), [109] 1.438(2), [110] 1.216 (48) [111] |
Ellipses, ε = 1.5 | 0.0043 [100] | 0.00431 | 2.059081(7) [109] |
Ellipses, ε = 5⁄3 | 0.65 [112] | 1.05 [112] | 2.28 [112] |
Ellipses, ε = 2 | 0.6287945(12), [109] 0.63 [112] | 0.991000(3), [109] 0.99 [112] | 2.523560(8), [109] 2.5 [112] |
Ellipses, ε = 3 | 0.56 [112] | 0.82 [112] | 3.157339(8), [109] 3.14 [112] |
Ellipses, ε = 4 | 0.5 [112] | 0.69 [112] | 3.569706(8), [109] 3.5 [112] |
Ellipses, ε = 5 | 0.455, [100] 0.455, [102] 0.46 [112] | 0.607 [100] | 3.861262(12), [109] 3.86 [100] |
Ellipses, ε = 6 | 4.079365(17) [109] | ||
Ellipses, ε = 7 | 4.249132(16) [109] | ||
Ellipses, ε = 8 | 4.385302(15) [109] | ||
Ellipses, ε = 9 | 4.497000(8) [109] | ||
Ellipses, ε = 10 | 0.301, [100] 0.303, [102] 0.30 [112] | 0.358 [100] 0.36 [112] | 4.590416(23) [109] 4.56, [100] 4.5 [112] |
Ellipses, ε = 15 | 4.894752(30) [109] | ||
Ellipses, ε = 20 | 0.178, [100] 0.17 [112] | 0.196 [100] | 5.062313(39), [109] 4.99 [100] |
Ellipses, ε = 50 | 0.081 [100] | 0.084 [100] | 5.393863(28), [109] 5.38 [100] |
Ellipses, ε = 100 | 0.0417 [100] | 0.0426 [100] | 5.513464(40), [109] 5.42 [100] |
Ellipses, ε = 200 | 0.021 [112] | 0.0212 [112] | 5.40 [112] |
Ellipses, ε = 1000 | 0.0043 [100] | 0.00431 | 5.624756(22), [109] 5.5 |
Superellipses, ε = 1, m = 1.5 | 0.671 [102] | ||
Superellipses, ε = 2.5, m = 1.5 | 0.599 [102] | ||
Superellipses, ε = 5, m = 1.5 | 0.469 [102] | ||
Superellipses, ε = 10, m = 1.5 | 0.322 [102] | ||
disco-rectangles, ε = 1.5 | 1.894 [108] | ||
disco-rectangles, ε = 2 | 2.245 [108] | ||
Aligned squares of side | 0.66675(2), [52] 0.66674349(3), [94] 0.66653(1), [113] 0.6666(4), [114] 0.668 [101] | 1.09884280(9), [94] 1.0982(3), [113] 1.098(1) [114] | 1.09884280(9), [94] 1.0982(3), [113] 1.098(1) [114] |
Randomly oriented squares | 0.62554075(4), [94] 0.6254(2) [114] 0.625, [102] | 0.9822723(1), [94] 0.9819(6) [114] 0.982278(14) [115] | 0.9822723(1), [94] 0.9819(6) [114] 0.982278(14) [115] |
Randomly oriented squares within angle | 0.6255(1) [114] | 0.98216(15) [114] | |
Rectangles, ε = 1.1 | 0.624870(7) | 0.980484(19) | 1.078532(21) [115] |
Rectangles, ε = 2 | 0.590635(5) | 0.893147(13) | 1.786294(26) [115] |
Rectangles, ε = 3 | 0.5405983(34) | 0.777830(7) | 2.333491(22) [115] |
Rectangles, ε = 4 | 0.4948145(38) | 0.682830(8) | 2.731318(30) [115] |
Rectangles, ε = 5 | 0.4551398(31), 0.451 [102] | 0.607226(6) | 3.036130(28) [115] |
Rectangles, ε = 10 | 0.3233507(25), 0.319 [102] | 0.3906022(37) | 3.906022(37) [115] |
Rectangles, ε = 20 | 0.2048518(22) | 0.2292268(27) | 4.584535(54) [115] |
Rectangles, ε = 50 | 0.09785513(36) | 0.1029802(4) | 5.149008(20) [115] |
Rectangles, ε = 100 | 0.0523676(6) | 0.0537886(6) | 5.378856(60) [115] |
Rectangles, ε = 200 | 0.02714526(34) | 0.02752050(35) | 5.504099(69) [115] |
Rectangles, ε = 1000 | 0.00559424(6) | 0.00560995(6) | 5.609947(60) [115] |
Sticks (needles) of length | 5.63726(2), [116] 5.6372858(6), [94] 5.637263(11), [115] 5.63724(18) [117] | ||
sticks with log-normal length dist. STD=0.5 | 4.756(3) [117] | ||
sticks with correlated angle dist. s=0.5 | 6.6076(4) [117] | ||
Power-law disks, x = 2.05 | 0.993(1) [118] | 4.90(1) | 0.0380(6) |
Power-law disks, x = 2.25 | 0.8591(5) [118] | 1.959(5) | 0.06930(12) |
Power-law disks, x = 2.5 | 0.7836(4) [118] | 1.5307(17) | 0.09745(11) |
Power-law disks, x = 4 | 0.69543(6) [118] | 1.18853(19) | 0.18916(3) |
Power-law disks, x = 5 | 0.68643(13) [118] | 1.1597(3) | 0.22149(8) |
Power-law disks, x = 6 | 0.68241(8) [118] | 1.1470(1) | 0.24340(5) |
Power-law disks, x = 7 | 0.6803(8) [118] | 1.140(6) | 0.25933(16) |
Power-law disks, x = 8 | 0.67917(9) [118] | 1.1368(5) | 0.27140(7) |
Power-law disks, x = 9 | 0.67856(12) [118] | 1.1349(4) | 0.28098(9) |
Voids around disks of radius r | 1 − Φc(disk) = 0.32355169(2), [94] 0.318(2), [119] 0.3261(6) [120] | ||
For disks, equals the critical number of disks per unit area, measured in units of the diameter , where is the number of objects and is the system size
For disks, equals critical total disk area.
gives the number of disk centers within the circle of influence (radius 2 r).
is the critical disk radius.
for ellipses of semi-major and semi-minor axes of a and b, respectively. Aspect ratio with .
for rectangles of dimensions and . Aspect ratio with .
for power-law distributed disks with , .
equals critical area fraction.
For disks, Ref. [99] use where is the density of disks of radius .
equals number of objects of maximum length per unit area.
For ellipses,
For void percolation, is the critical void fraction.
For more ellipse values, see [109] [112]
For more rectangle values, see [115]
Both ellipses and rectangles belong to the superellipses, with . For more percolation values of superellipses, see. [102]
For the monodisperse particle systems, the percolation thresholds of concave-shaped superdisks are obtained as seen in [121]
Lattice | z | Site percolation threshold | Bond percolation threshold | |
---|---|---|---|---|
Relative neighborhood graph | 2.5576 | 0.796(2) [124] | 0.771(2) [124] | |
Voronoi tessellation | 3 | 0.71410(2), [126] 0.7151* [69] | 0.68, [127] 0.6670(1), [128] 0.6680(5), [129] 0.666931(5) [126] | |
Voronoi covering/medial | 4 | 0.666931(2) [126] [128] | 0.53618(2) [126] | |
Randomized kagome/square-octagon, fraction r=1⁄2 | 4 | 0.6599 [16] | ||
Penrose rhomb dual | 4 | 0.6381(3) [66] | 0.5233(2) [66] | |
Gabriel graph | 4 | 0.6348(8), [130] 0.62 [131] | 0.5167(6), [130] 0.52 [131] | |
Random-line tessellation, dual | 4 | 0.586(2) [132] | ||
Penrose rhomb | 4 | 0.5837(3), [66] 0.0.5610(6) (weighted bonds) [133] 0.58391(1) [134] | 0.483(5), [135] 0.4770(2) [66] | |
Octagonal lattice, "chemical" links (Ammann–Beenker tiling) | 4 | 0.585 [136] | 0.48 [136] | |
Octagonal lattice, "ferromagnetic" links | 5.17 | 0.543 [136] | 0.40 [136] | |
Dodecagonal lattice, "chemical" links | 3.63 | 0.628 [136] | 0.54 [136] | |
Dodecagonal lattice, "ferromagnetic" links | 4.27 | 0.617 [136] | 0.495 [136] | |
Delaunay triangulation | 6 | 1⁄2 [137] | 0.3333(1) [128] 0.3326(5), [129] 0.333069(2) [126] | |
Uniform Infinite Planar Triangulation [138] | 6 | 1⁄2 | (2√3 – 1)/11 ≈ 0.2240 [125] [139] | |
*Theoretical estimate
Assuming power-law correlations
lattice | α | Site percolation threshold | Bond percolation threshold |
---|---|---|---|
square | 3 | 0.561406(4) [140] | |
square | 2 | 0.550143(5) [140] | |
square | 0.1 | 0.508(4) [140] | |
h is the thickness of the slab, h × ∞ × ∞. Boundary conditions (b.c.) refer to the top and bottom planes of the slab.
Lattice | h | z | Site percolation threshold | Bond percolation threshold | |
---|---|---|---|---|---|
simple cubic (open b.c.) | 2 | 5 | 5 | 0.47424, [141] 0.4756 [142] | |
bcc (open b.c.) | 2 | 0.4155 [142] | |||
hcp (open b.c.) | 2 | 0.2828 [142] | |||
diamond (open b.c.) | 2 | 0.5451 [142] | |||
simple cubic (open b.c.) | 3 | 0.4264 [142] | |||
bcc (open b.c.) | 3 | 0.3531 [142] | |||
bcc (periodic b.c.) | 3 | 0.21113018(38) [143] | |||
hcp (open b.c.) | 3 | 0.2548 [142] | |||
diamond (open b.c.) | 3 | 0.5044 [142] | |||
simple cubic (open b.c.) | 4 | 0.3997, [141] 0.3998 [142] | |||
bcc (open b.c.) | 4 | 0.3232 [142] | |||
bcc (periodic b.c.) | 4 | 0.20235168(59) [143] | |||
hcp (open b.c.) | 4 | 0.2405 [142] | |||
diamond (open b.c.) | 4 | 0.4842 [142] | |||
simple cubic (periodic b.c.) | 5 | 6 | 6 | 0.278102(5) [143] | |
simple cubic (open b.c.) | 6 | 0.3708 [142] | |||
simple cubic (periodic b.c.) | 6 | 6 | 6 | 0.272380(2) [143] | |
bcc (open b.c.) | 6 | 0.2948 [142] | |||
hcp (open b.c.) | 6 | 0.2261 [142] | |||
diamond (open b.c.) | 6 | 0.4642 [142] | |||
simple cubic (periodic b.c.) | 7 | 6 | 6 | 0.3459514(12) [143] | 0.268459(1) [143] |
simple cubic (open b.c.) | 8 | 0.3557, [141] 0.3565 [142] | |||
simple cubic (periodic b.c.) | 8 | 6 | 6 | 0.265615(5) [143] | |
bcc (open b.c.) | 8 | 0.2811 [142] | |||
hcp (open b.c.) | 8 | 0.2190 [142] | |||
diamond (open b.c.) | 8 | 0.4549 [142] | |||
simple cubic (open b.c.) | 12 | 0.3411 [142] | |||
bcc (open b.c.) | 12 | 0.2688 [142] | |||
hcp (open b.c.) | 12 | 0.2117 [142] | |||
diamond (open b.c.) | 12 | 0.4456 [142] | |||
simple cubic (open b.c.) | 16 | 0.3219, [141] 0.3339 [142] | |||
bcc (open b.c.) | 16 | 0.2622 [142] | |||
hcp (open b.c.) | 16 | 0.2086 [142] | |||
diamond (open b.c.) | 16 | 0.4415 [142] | |||
simple cubic (open b.c.) | 32 | 0.3219, [141] | |||
simple cubic (open b.c.) | 64 | 0.3165, [141] | |||
simple cubic (open b.c.) | 128 | 0.31398, [141] | |||
Lattice | z | filling factor* | filling fraction* | Site percolation threshold | Bond percolation threshold | |
---|---|---|---|---|---|---|
(10,3)-a oxide (or site-bond) [144] | 23 32 | 2.4 | 0.748713(22) [144] | = (pc,bond(10,3) – a)1⁄2 = 0.742334(25) [145] | ||
(10,3)-b oxide (or site-bond) [144] | 23 32 | 2.4 | 0.233 [146] | 0.174 | 0.745317(25) [144] | = (pc,bond(10,3) – b)1⁄2 = 0.739388(22) [145] |
silicon dioxide (diamond site-bond) [144] | 4,22 | 2 2⁄3 | 0.638683(35) [144] | |||
Modified (10,3)-b [147] | 32,2 | 2 2⁄3 | 0.627 [147] | |||
(8,3)-a [145] | 3 | 3 | 0.577962(33) [145] | 0.555700(22) [145] | ||
(10,3)-a [145] gyroid [148] | 3 | 3 | 0.571404(40) [145] | 0.551060(37) [145] | ||
(10,3)-b [145] | 3 | 3 | 0.565442(40) [145] | 0.546694(33) [145] | ||
cubic oxide (cubic site-bond) [144] | 6,23 | 3.5 | 0.524652(50) [144] | |||
bcc dual | 4 | 0.4560(6) [149] | 0.4031(6) [149] | |||
ice Ih | 4 | 4 | π √3 / 16 = 0.340087 | 0.147 | 0.433(11) [150] | 0.388(10) [151] |
diamond (Ice Ic) | 4 | 4 | π √3 / 16 = 0.340087 | 0.1462332 | 0.4299(8), [152] 0.4299870(4), [153] 0.426+0.08 −0.02, [154] 0.4297(4) [155] 0.4301(4), [156] 0.428(4), [157] 0.425(15), [158] 0.425, [41] [48] 0.436(12) [150] | 0.3895892(5), [153] 0.3893(2), [156] 0.3893(3), [155] 0.388(5), [158] 0.3886(5), [152] 0.388(5) [157] 0.390(11) [151] |
diamond dual | 6 2⁄3 | 0.3904(5) [149] | 0.2350(5) [149] | |||
3D kagome (covering graph of the diamond lattice) | 6 | π √2 / 12 = 0.37024 | 0.1442 | 0.3895(2) [159] =pc(site) for diamond dual and pc(bond) for diamond lattice [149] | 0.2709(6) [149] | |
Bow-tie stack dual | 5 1⁄3 | 0.3480(4) [38] | 0.2853(4) [38] | |||
honeycomb stack | 5 | 5 | 0.3701(2) [38] | 0.3093(2) [38] | ||
octagonal stack dual | 5 | 5 | 0.3840(4) [38] | 0.3168(4) [38] | ||
pentagonal stack | 5 1⁄3 | 0.3394(4) [38] | 0.2793(4) [38] | |||
kagome stack | 6 | 6 | 0.453450 | 0.1517 | 0.3346(4) [38] | 0.2563(2) [38] |
fcc dual | 42,8 | 5 1⁄3 | 0.3341(5) [149] | 0.2703(3) [149] | ||
simple cubic | 6 | 6 | π / 6 = 0.5235988 | 0.1631574 | 0.307(10), [158] 0.307, [41] 0.3115(5), [160] 0.3116077(2), [161] 0.311604(6), [162] 0.311605(5), [163] 0.311600(5), [164] 0.3116077(4), [165] 0.3116081(13), [166] 0.3116080(4), [167] 0.3116060(48), [168] 0.3116004(35), [169] 0.31160768(15) [153] | 0.247(5), [158] 0.2479(4), [152] 0.2488(2), [170] 0.24881182(10), [161] 0.2488125(25), [171] 0.2488126(5), [172] |
hcp dual | 44,82 | 5 1⁄3 | 0.3101(5) [149] | 0.2573(3) [149] | ||
dice stack | 5,8 | 6 | π √3 / 9 = 0.604600 | 0.1813 | 0.2998(4) [38] | 0.2378(4) [38] |
bow-tie stack | 7 | 7 | 0.2822(6) [38] | 0.2092(4) [38] | ||
Stacked triangular / simple hexagonal | 8 | 8 | 0.26240(5), [173] 0.2625(2), [174] 0.2623(2) [38] | 0.18602(2), [173] 0.1859(2) [38] | ||
octagonal (union-jack) stack | 6,10 | 8 | 0.2524(6) [38] | 0.1752(2) [38] | ||
bcc | 8 | 8 | 0.243(10), [158] 0.243, [41] 0.2459615(10), [167] 0.2460(3), [175] 0.2464(7), [152] 0.2458(2) [156] | 0.178(5), [158] 0.1795(3), [152] 0.18025(15), [170] 0.1802875(10) [172] | ||
simple cubic with 3NN (same as bcc) | 8 | 8 | 0.2455(1), [176] 0.2457(7) [177] | |||
fcc, D3 | 12 | 12 | π / (3 √2) = 0.740480 | 0.147530 | 0.195, [41] 0.198(3), [178] 0.1998(6), [152] 0.1992365(10), [167] 0.19923517(20), [153] 0.1994(2), [156] 0.199236(4) [179] | 0.1198(3), [152] 0.1201635(10) [172] 0.120169(2) [179] |
hcp | 12 | 12 | π / (3 √2) = 0.740480 | 0.147545 | 0.195(5), [158] 0.1992555(10) [180] | 0.1201640(10), [180] 0.119(2) [158] |
La2−x Srx Cu O4 | 12 | 12 | 0.19927(2) [181] | |||
simple cubic with 2NN (same as fcc) | 12 | 12 | 0.1991(1) [176] | |||
simple cubic with NN+4NN | 12 | 12 | 0.15040(12), [182] 0.1503793(7) [183] | 0.1068263(7) [184] | ||
simple cubic with 3NN+4NN | 14 | 14 | 0.20490(12) [182] | 0.1012133(7) [184] | ||
bcc NN+2NN (= sc(3,4) sc-3NN+4NN) | 14 | 14 | 0.175, [41] 0.1686,(20) [185] 0.1759432(8) | 0.0991(5), [185] 0.1012133(7), [45] 0.1759432(8) [45] | ||
Nanotube fibers on FCC | 14 | 14 | 0.1533(13) [186] | |||
simple cubic with NN+3NN | 14 | 14 | 0.1420(1) [176] | 0.0920213(7) [184] | ||
simple cubic with 2NN+4NN | 18 | 18 | 0.15950(12) [182] | 0.0751589(9) [184] | ||
simple cubic with NN+2NN | 18 | 18 | 0.137, [48] 0.136, [187] 0.1372(1), [176] 0.13735(5),[ citation needed ] 0.1373045(5) [45] | 0.0752326(6) [184] | ||
fcc with NN+2NN (=sc-2NN+4NN) | 18 | 18 | 0.136, [41] 0.1361408(8) [45] | 0.0751589(9) [45] | ||
simple cubic with short-length correlation | 6+ | 6+ | 0.126(1) [188] | |||
simple cubic with NN+3NN+4NN | 20 | 20 | 0.11920(12) [182] | 0.0624379(9) [184] | ||
simple cubic with 2NN+3NN | 20 | 20 | 0.1036(1) [176] | 0.0629283(7) [184] | ||
simple cubic with NN+2NN+4NN | 24 | 24 | 0.11440(12) [182] | 0.0533056(6) [184] | ||
simple cubic with 2NN+3NN+4NN | 26 | 26 | 0.11330(12) [182] | 0.0474609(9) | ||
simple cubic with NN+2NN+3NN | 26 | 26 | 0.097, [41] 0.0976(1), [176] 0.0976445(10), 0.0976444(6) [45] | 0.0497080(10) [184] | ||
bcc with NN+2NN+3NN | 26 | 26 | 0.095, [48] 0.0959084(6) [45] | 0.0492760(10) [45] | ||
simple cubic with NN+2NN+3NN+4NN | 32 | 32 | 0.10000(12), [182] 0.0801171(9) [45] | 0.0392312(8) [184] | ||
fcc with NN+2NN+3NN | 42 | 42 | 0.061, [48] 0.0610(5), [187] 0.0618842(8) [45] | 0.0290193(7) [45] | ||
fcc with NN+2NN+3NN+4NN | 54 | 54 | 0.0500(5) [187] | |||
sc-1,2,3,4,5 simple cubic with NN+2NN+3NN+4NN+5NN | 56 | 56 | 0.0461815(5) [45] | 0.0210977(7) [45] | ||
sc-1,...,6 (2x2x2 cube [51] ) | 80 | 80 | 0.0337049(9), [45] 0.03373(13) [51] | 0.0143950(10) [45] | ||
sc-1,...,7 | 92 | 92 | 0.0290800(10) [45] | 0.0123632(8) [45] | ||
sc-1,...,8 | 122 | 122 | 0.0218686(6) [45] | 0.0091337(7) [45] | ||
sc-1,...,9 | 146 | 146 | 0.0184060(10) [45] | 0.0075532(8) [45] | ||
sc-1,...,10 | 170 | 170 | 0.0064352(8) [45] | |||
sc-1,...,11 | 178 | 178 | 0.0061312(8) [45] | |||
sc-1,...,12 | 202 | 202 | 0.0053670(10) [45] | |||
sc-1,...,13 | 250 | 250 | 0.0042962(8) [45] | |||
3x3x3 cube | 274 | 274 | φc= 0.76564(1), [52] pc = 0.0098417(7), [52] 0.009854(6) [51] | |||
4x4x4 cube | 636 | 636 | φc=0.76362(1), [52] pc = 0.0042050(2), [52] 0.004217(3) [51] | |||
5x5x5 cube | 1214 | 1250 | φc=0.76044(2), [52] pc = 0.0021885(2), [52] 0.002185(4) [51] | |||
6x6x6 cube | 2056 | 2056 | 0.001289(2) [51] | |||
Filling factor = fraction of space filled by touching spheres at every lattice site (for systems with uniform bond length only). Also called Atomic Packing Factor.
Filling fraction (or Critical Filling Fraction) = filling factor * pc(site).
NN = nearest neighbor, 2NN = next-nearest neighbor, 3NN = next-next-nearest neighbor, etc.
kxkxk cubes are cubes of occupied sites on a lattice, and are equivalent to extended-range percolation of a cube of length (2k+1), with edges and corners removed, with z = (2k+1)3-12(2k-1)-9 (center site not counted in z).
Question: the bond thresholds for the hcp and fcc lattice agree within the small statistical error. Are they identical, and if not, how far apart are they? Which threshold is expected to be bigger? Similarly for the ice and diamond lattices. See [189]
System | polymer Φc |
---|---|
percolating excluded volume of athermal polymer matrix (bond-fluctuation model on cubic lattice) | 0.4304(3) [190] |
Here, one distorts a regular lattice of unit spacing by moving vertices uniformly within the cube , and considers percolation when sites are within Euclidean distance of each other.
Lattice | Site percolation threshold | Bond percolation threshold | |||
---|---|---|---|---|---|
cubic | 0.05 | 1.0 | 0.60254(3) [191] | ||
0.1 | 1.00625 | 0.58688(4) [191] | |||
0.15 | 1.025 | 0.55075(2) [191] | |||
0.175 | 1.05 | 0.50645(5) [191] | |||
0.2 | 1.1 | 0.44342(3) [191] | |||
Site threshold is the number of overlapping objects per lattice site. The coverage φc is the net fraction of sites covered, and v is the volume (number of cubes). Overlapping cubes are given in the section on thresholds of 3D lattices. Here z is the coordination number to k-mers of either orientation, with
System | k | z | Site coverage φc | Site percolation threshold pc |
---|---|---|---|---|
1 x 2 dimer, cubic lattice | 2 | 56 | 0.24542 [51] | 0.045847(2) [51] |
1 x 3 trimer, cubic lattice | 3 | 104 | 0.19578 [51] | 0.023919(9) [51] |
1 x 4 stick, cubic lattice | 4 | 164 | 0.16055 [51] | 0.014478(7) [51] |
1 x 5 stick, cubic lattice | 5 | 236 | 0.13488 [51] | 0.009613(8) [51] |
1 x 6 stick, cubic lattice | 6 | 320 | 0.11569 [51] | 0.006807(2) [51] |
2 x 2 plaquette, cubic lattice | 2 | 0.22710 [51] | 0.021238(2) [51] | |
3 x 3 plaquette, cubic lattice | 3 | 0.18686 [51] | 0.007632(5) [51] | |
4 x 4 plaquette, cubic lattice | 4 | 0.16159 [51] | 0.003665(3) [51] | |
5 x 5 plaquette, cubic lattice | 5 | 0.14316 [51] | 0.002058(5) [51] | |
6 x 6 plaquette, cubic lattice | 6 | 0.12900 [51] | 0.001278(5) [51] | |
The coverage is calculated from by for sticks, and for plaquettes.
System | Site percolation threshold | Bond percolation threshold |
---|---|---|
Simple cubic | 0.2555(1) [192] | |
All overlapping except for jammed spheres and polymer matrix.
System | Φc | ηc |
---|---|---|
Spheres of radius r | 0.289, [193] 0.293, [194] 0.286, [195] 0.295. [101] 0.2895(5), [196] 0.28955(7), [197] 0.2896(7), [198] 0.289573(2), [199] 0.2896, [200] 0.2854, [201] 0.290, [202] 0.290 [203] | 0.3418(7), [196] 0.3438(13), [204] 0.341889(3), [199] 0.3360, [201] 0.34189(2) [113] [corrected], 0.341935(8), [205] 0.335, [206] |
Oblate ellipsoids with major radius r and aspect ratio 4⁄3 | 0.2831 [201] | 0.3328 [201] |
Prolate ellipsoids with minor radius r and aspect ratio 3⁄2 | 0.2757, [200] 0.2795, [201] 0.2763 [202] | 0.3278 [201] |
Oblate ellipsoids with major radius r and aspect ratio 2 | 0.2537, [200] 0.2629, [201] 0.254 [202] | 0.3050 [201] |
Prolate ellipsoids with minor radius r and aspect ratio 2 | 0.2537, [200] 0.2618, [201] 0.25(2), [207] 0.2507 [202] | 0.3035, [201] 0.29(3) [207] |
Oblate ellipsoids with major radius r and aspect ratio 3 | 0.2289 [201] | 0.2599 [201] |
Prolate ellipsoids with minor radius r and aspect ratio 3 | 0.2033, [200] 0.2244, [201] 0.20(2) [207] | 0.2541, [201] 0.22(3) [207] |
Oblate ellipsoids with major radius r and aspect ratio 4 | 0.2003 [201] | 0.2235 [201] |
Prolate ellipsoids with minor radius r and aspect ratio 4 | 0.1901, [201] 0.16(2) [207] | 0.2108, [201] 0.17(3) [207] |
Oblate ellipsoids with major radius r and aspect ratio 5 | 0.1757 [201] | 0.1932 [201] |
Prolate ellipsoids with minor radius r and aspect ratio 5 | 0.1627, [201] 0.13(2) [207] | 0.1776, [201] 0.15(2) [207] |
Oblate ellipsoids with major radius r and aspect ratio 10 | 0.0895, [200] 0.1058 [201] | 0.1118 [201] |
Prolate ellipsoids with minor radius r and aspect ratio 10 | 0.0724, [200] 0.08703, [201] 0.07(2) [207] | 0.09105, [201] 0.07(2) [207] |
Oblate ellipsoids with major radius r and aspect ratio 100 | 0.01248 [201] | 0.01256 [201] |
Prolate ellipsoids with minor radius r and aspect ratio 100 | 0.006949 [201] | 0.006973 [201] |
Oblate ellipsoids with major radius r and aspect ratio 1000 | 0.001275 [201] | 0.001276 [201] |
Oblate ellipsoids with major radius r and aspect ratio 2000 | 0.000637 [201] | 0.000637 [201] |
Spherocylinders with H/D = 1 | 0.2439(2) [198] | |
Spherocylinders with H/D = 4 | 0.1345(1) [198] | |
Spherocylinders with H/D = 10 | 0.06418(20) [198] | |
Spherocylinders with H/D = 50 | 0.01440(8) [198] | |
Spherocylinders with H/D = 100 | 0.007156(50) [198] | |
Spherocylinders with H/D = 200 | 0.003724(90) [198] | |
Aligned cylinders | 0.2819(2) [208] | 0.3312(1) [208] |
Aligned cubes of side | 0.2773(2) [114] 0.27727(2), [52] 0.27730261(79) [168] | 0.3247(3), [113] 0.3248(3), [114] 0.32476(4) [208] 0.324766(1) [168] |
Randomly oriented icosahedra | 0.3030(5) [209] | |
Randomly oriented dodecahedra | 0.2949(5) [209] | |
Randomly oriented octahedra | 0.2514(6) [209] | |
Randomly oriented cubes of side | 0.2168(2) [114] 0.2174, [200] | 0.2444(3), [114] 0.2443(5) [209] |
Randomly oriented tetrahedra | 0.1701(7) [209] | |
Randomly oriented disks of radius r (in 3D) | 0.9614(5) [210] | |
Randomly oriented square plates of side | 0.8647(6) [210] | |
Randomly oriented triangular plates of side | 0.7295(6) [210] | |
Jammed spheres (average z = 6) | 0.183(3), [211] 0.1990, [212] see also contact network of jammed spheres below. | 0.59(1) [211] (volume fraction of all spheres) |
is the total volume (for spheres), where N is the number of objects and L is the system size.
is the critical volume fraction, valid for overlapping randomly placed objects.
For disks and plates, these are effective volumes and volume fractions.
For void ("Swiss-Cheese" model), is the critical void fraction.
For more results on void percolation around ellipsoids and elliptical plates, see. [213]
For more ellipsoid percolation values see. [201]
For spherocylinders, H/D is the ratio of the height to the diameter of the cylinder, which is then capped by hemispheres. Additional values are given in. [198]
For superballs, m is the deformation parameter, the percolation values are given in., [214] [215] In addition, the thresholds of concave-shaped superballs are also determined in [121]
For cuboid-like particles (superellipsoids), m is the deformation parameter, more percolation values are given in. [200]
Void percolation refers to percolation in the space around overlapping objects. Here refers to the fraction of the space occupied by the voids (not of the particles) at the critical point, and is related to by . is defined as in the continuum percolation section above.
System | Φc | ηc |
---|---|---|
Voids around disks of radius r | 22.86(2) [213] | |
Voids around randomly oriented tetrahedra | 0.0605(6) [216] | |
Voids around oblate ellipsoids of major radius r and aspect ratio 32 | 0.5308(7) [217] | 0.6333 [217] |
Voids around oblate ellipsoids of major radius r and aspect ratio 16 | 0.3248(5) [217] | 1.125 [217] |
Voids around oblate ellipsoids of major radius r and aspect ratio 10 | 1.542(1) [213] | |
Voids around oblate ellipsoids of major radius r and aspect ratio 8 | 0.1615(4) [217] | 1.823 [217] |
Voids around oblate ellipsoids of major radius r and aspect ratio 4 | 0.0711(2) [217] | 2.643, [217] 2.618(5) [213] |
Voids around oblate ellipsoids of major radius r and aspect ratio 2 | 3.239(4) [213] | |
Voids around prolate ellipsoids of aspect ratio 8 | 0.0415(7) [218] | |
Voids around prolate ellipsoids of aspect ratio 6 | 0.0397(7) [218] | |
Voids around prolate ellipsoids of aspect ratio 4 | 0.0376(7) [218] | |
Voids around prolate ellipsoids of aspect ratio 3 | 0.03503(50) [218] | |
Voids around prolate ellipsoids of aspect ratio 2 | 0.0323(5) [218] | |
Voids around aligned square prisms of aspect ratio 2 | 0.0379(5) [219] | |
Voids around randomly oriented square prisms of aspect ratio 20 | 0.0534(4) [219] | |
Voids around randomly oriented square prisms of aspect ratio 15 | 0.0535(4) [219] | |
Voids around randomly oriented square prisms of aspect ratio 10 | 0.0524(5) [219] | |
Voids around randomly oriented square prisms of aspect ratio 8 | 0.0523(6) [219] | |
Voids around randomly oriented square prisms of aspect ratio 7 | 0.0519(3) [219] | |
Voids around randomly oriented square prisms of aspect ratio 6 | 0.0519(5) [219] | |
Voids around randomly oriented square prisms of aspect ratio 5 | 0.0515(7) [219] | |
Voids around randomly oriented square prisms of aspect ratio 4 | 0.0505(7) [219] | |
Voids around randomly oriented square prisms of aspect ratio 3 | 0.0485(11) [219] | |
Voids around randomly oriented square prisms of aspect ratio 5/2 | 0.0483(8) [219] | |
Voids around randomly oriented square prisms of aspect ratio 2 | 0.0465(7) [219] | |
Voids around randomly oriented square prisms of aspect ratio 3/2 | 0.0461(14) [219] | |
Voids around hemispheres | 0.0455(6) [220] | |
Voids around aligned tetrahedra | 0.0605(6) [216] | |
Voids around randomly oriented tetrahedra | 0.0605(6) [216] | |
Voids around aligned cubes | 0.036(1), [52] 0.0381(3) [216] | |
Voids around randomly oriented cubes | 0.0452(6), [216] 0.0449(5) [219] | |
Voids around aligned octahedra | 0.0407(3) [216] | |
Voids around randomly oriented octahedra | 0.0398(5) [216] | |
Voids around aligned dodecahedra | 0.0356(3) [216] | |
Voids around randomly oriented dodecahedra | 0.0360(3) [216] | |
Voids around aligned icosahedra | 0.0346(3) [216] | |
Voids around randomly oriented icosahedra | 0.0336(7) [216] | |
Voids around spheres | 0.034(7), [221] 0.032(4), [222] 0.030(2), [119] 0.0301(3), [223] 0.0294, [218] 0.0300(3), [224] 0.0317(4), [225] 0.0308(5) [220] 0.0301(1), [217] 0.0301(1) [216] | 3.506(8), [224] 3.515(6), [213] 3.510(2) [105] |
Lattice | z | Site percolation threshold | Bond percolation threshold | |
---|---|---|---|---|
Contact network of packed spheres | 6 | 0.310(5), [211] 0.287(50), [226] 0.3116(3), [212] | ||
Random-plane tessellation, dual | 6 | 0.290(7) [227] | ||
Icosahedral Penrose | 6 | 0.285 [228] | 0.225 [228] | |
Penrose w/2 diagonals | 6.764 | 0.271 [228] | 0.207 [228] | |
Penrose w/8 diagonals | 12.764 | 0.188 [228] | 0.111 [228] | |
Voronoi network | 15.54 | 0.1453(20) [185] | 0.0822(50) [185] |
Lattice | z | Site percolation threshold | Critical coverage fraction | Bond percolation threshold | |
---|---|---|---|---|---|
Drilling percolation, simple cubic lattice* | 6 | 6 | 0.6345(3), [229] 0.6339(5), [230] 0.633965(15) [231] | 0.25480 | |
Drill in z direction on cubic lattice, remove single sites | 6 | 6 | 0.592746 (columns), 0.4695(10) (sites) [232] | 0.2784 | |
Random tube model, simple cubic lattice† | 0.231456(6) [233] | ||||
Pac-Man percolation, simple cubic lattice | 0.139(6) [234] | ||||
In drilling percolation, the site threshold represents the fraction of columns in each direction that have not been removed, and . For the 1d drilling, we have (columns) (sites).
† In tube percolation, the bond threshold represents the value of the parameter such that the probability of putting a bond between neighboring vertical tube segments is , where is the overlap height of two adjacent tube segments. [233]
d | System | Φc | ηc |
---|---|---|---|
4 | Overlapping hyperspheres | 0.1223(4) [113] | 0.1300(13), [204] 0.1304(5) [113] |
4 | Aligned hypercubes | 0.1132(5), [113] 0.1132348(17) [168] | 0.1201(6) [113] |
4 | Voids around hyperspheres | 0.00211(2) [120] | 6.161(10) [120] 6.248(2), [105] |
5 | Overlapping hyperspheres | 0.0544(6), [204] 0.05443(7) [113] | |
5 | Aligned hypercubes | 0.04900(7), [113] 0.0481621(13) [168] | 0.05024(7) [113] |
5 | Voids around hyperspheres | 1.26(6)x10−4 [120] | 8.98(4), [120] 9.170(8) [105] |
6 | Overlapping hyperspheres | 0.02391(31), [204] 0.02339(5) [113] | |
6 | Aligned hypercubes | 0.02082(8), [113] 0.0213479(10) [168] | 0.02104(8) [113] |
6 | Voids around hyperspheres | 8.0(6)x10−6 [120] | 11.74(8), [120] 12.24(2), [105] |
7 | Overlapping hyperspheres | 0.01102(16), [204] 0.01051(3) [113] | |
7 | Aligned hypercubes | 0.00999(5), [113] 0.0097754(31) [168] | 0.01004(5) [113] |
7 | Voids around hyperspheres | 15.46(5) [105] | |
8 | Overlapping hyperspheres | 0.00516(8), [204] 0.004904(6) [113] | |
8 | Aligned hypercubes | 0.004498(5) [113] | |
8 | Voids around hyperspheres | 18.64(8) [105] | |
9 | Overlapping hyperspheres | 0.002353(4) [113] | |
9 | Aligned hypercubes | 0.002166(4) [113] | |
9 | Voids around hyperspheres | 22.1(4) [105] | |
10 | Overlapping hyperspheres | 0.001138(3) [113] | |
10 | Aligned hypercubes | 0.001058(4) [113] | |
11 | Overlapping hyperspheres | 0.0005530(3) [113] | |
11 | Aligned hypercubes | 0.0005160(3) [113] |
In 4d, .
In 5d, .
In 6d, .
is the critical volume fraction, valid for overlapping objects.
For void models, is the critical void fraction, and is the total volume of the overlapping objects
d | z | Site thresholds | Bond thresholds |
---|---|---|---|
4 | 8 | 0.198(1) [235] 0.197(6), [236] 0.1968861(14), [237] 0.196889(3), [238] 0.196901(5), [239] 0.19680(23), [240] 0.1968904(65), [168] 0.19688561(3) [241] | 0.1600(1), [242] 0.16005(15), [170] 0.1601314(13), [237] 0.160130(3), [238] 0.1601310(10), [171] 0.1601312(2), [243] 0.16013122(6) [241] |
5 | 10 | 0.141(1),0.198(1) [235] 0.141(3), [236] 0.1407966(15), [237] 0.1407966(26), [168] 0.14079633(4) [241] | 0.1181(1), [242] 0.118(1), [244] 0.11819(4), [170] 0.118172(1), [237] 0.1181718(3) [171] 0.11817145(3) [241] |
6 | 12 | 0.106(1), [235] 0.108(3), [236] 0.109017(2), [237] 0.1090117(30), [168] 0.109016661(8) [241] | 0.0943(1), [242] 0.0942(1), [245] 0.0942019(6), [237] 0.09420165(2) [241] |
7 | 14 | 0.05950(5), [245] 0.088939(20), [246] 0.0889511(9), [237] 0.0889511(90), [168] 0.088951121(1), [241] | 0.0787(1), [242] 0.078685(30), [245] 0.0786752(3), [237] 0.078675230(2) [241] |
8 | 16 | 0.0752101(5), [237] 0.075210128(1) [241] | 0.06770(5), [245] 0.06770839(7), [237] 0.0677084181(3) [241] |
9 | 18 | 0.0652095(3), [237] 0.0652095348(6) [241] | 0.05950(5), [245] 0.05949601(5), [237] 0.0594960034(1) [241] |
10 | 20 | 0.0575930(1), [237] 0.0575929488(4) [241] | 0.05309258(4), [237] 0.0530925842(2) [241] |
11 | 22 | 0.05158971(8), [237] 0.0515896843(2) [241] | 0.04794969(1), [237] 0.04794968373(8) [241] |
12 | 24 | 0.04673099(6), [237] 0.0467309755(1) [241] | 0.04372386(1), [237] 0.04372385825(10) [241] |
13 | 26 | 0.04271508(8), [237] 0.04271507960(10) [241] | 0.04018762(1), [237] 0.04018761703(6) [241] |
For thresholds on high dimensional hypercubic lattices, we have the asymptotic series expansions [236] [244] [247]
where . For 13-dimensional bond percolation, for example, the error with the measured value is less than 10−6, and these formulas can be useful for higher-dimensional systems.
d | lattice | z | Site thresholds | Bond thresholds |
---|---|---|---|---|
4 | diamond | 5 | 0.2978(2) [156] | 0.2715(3) [156] |
4 | kagome | 8 | 0.2715(3) [159] | 0.177(1) [156] |
4 | bcc | 16 | 0.1037(3) [156] | 0.074(1), [156] 0.074212(1) [243] |
4 | fcc, D4, hypercubic 2NN | 24 | 0.0842(3), [156] 0.08410(23), [240] 0.0842001(11) [179] | 0.049(1), [156] 0.049517(1), [243] 0.0495193(8) [179] |
4 | hypercubic NN+2NN | 32 | 0.06190(23), [240] 0.0617731(19) [248] | 0.035827(1), [243] 0.0338047(27) [248] |
4 | hypercubic 3NN | 32 | 0.04540(23) [240] | |
4 | hypercubic NN+3NN | 40 | 0.04000(23) [240] | 0.0271892(22) [248] |
4 | hypercubic 2NN+3NN | 56 | 0.03310(23) [240] | 0.0194075(15) [248] |
4 | hypercubic NN+2NN+3NN | 64 | 0.03190(23), [240] 0.0319407(13) [248] | 0.0171036(11) [248] |
4 | hypercubic NN+2NN+3NN+4NN | 88 | 0.0231538(12) [248] | 0.0122088(8) [248] |
4 | hypercubic NN+...+5NN | 136 | 0.0147918(12) [248] | 0.0077389(9) [248] |
4 | hypercubic NN+...+6NN | 232 | 0.0088400(10) [248] | 0.0044656(11) [248] |
4 | hypercubic NN+...+7NN | 296 | 0.0070006(6) [248] | 0.0034812(7) [248] |
4 | hypercubic NN+...+8NN | 320 | 0.0064681(9) [248] | 0.0032143(8) [248] |
4 | hypercubic NN+...+9NN | 424 | 0.0048301(9) [248] | 0.0024117(7) [248] |
5 | diamond | 6 | 0.2252(3) [156] | 0.2084(4) [159] |
5 | kagome | 10 | 0.2084(4) [159] | 0.130(2) [156] |
5 | bcc | 32 | 0.0446(4) [156] | 0.033(1) [156] |
5 | fcc, D5, hypercubic 2NN | 40 | 0.0431(3), [156] 0.0435913(6) [179] | 0.026(2), [156] 0.0271813(2) [179] |
5 | hypercubic NN+2NN | 50 | 0.0334(2) [249] | 0.0213(1) [249] |
6 | diamond | 7 | 0.1799(5) [156] | 0.1677(7) [159] |
6 | kagome | 12 | 0.1677(7) [159] | |
6 | fcc, D6 | 60 | 0.0252(5), [156] 0.02602674(12) [179] | 0.01741556(5) [179] |
6 | bcc | 64 | 0.0199(5) [156] | |
6 | E6 [179] | 72 | 0.02194021(14) [179] | 0.01443205(8) [179] |
7 | fcc, D7 | 84 | 0.01716730(5) [179] | 0.012217868(13) [179] |
7 | E7 [179] | 126 | 0.01162306(4) [179] | 0.00808368(2) [179] |
8 | fcc, D8 | 112 | 0.01215392(4) [179] | 0.009081804(6) [179] |
8 | E8 [179] | 240 | 0.00576991(2) [179] | 0.004202070(2) [179] |
9 | fcc, D9 | 144 | 0.00905870(2) [179] | 0.007028457(3) [179] |
9 | [179] | 272 | 0.00480839(2) [179] | 0.0037006865(11) [179] |
10 | fcc, D10 | 180 | 0.007016353(9) [179] | 0.005605579(6) [179] |
11 | fcc, D11 | 220 | 0.005597592(4) [179] | 0.004577155(3) [179] |
12 | fcc, D12 | 264 | 0.004571339(4) [179] | 0.003808960(2) [179] |
13 | fcc, D13 | 312 | 0.003804565(3) [179] | 0.0032197013(14) [179] |
In a one-dimensional chain we establish bonds between distinct sites and with probability decaying as a power-law with an exponent . Percolation occurs [250] [251] at a critical value for . The numerically determined percolation thresholds are given by: [252]
Critical thresholds as a function of . [252] The dotted line is the rigorous lower bound. [250] | ||
0.1 | 0.047685(8) | |
0.2 | 0.093211(16) | |
0.3 | 0.140546(17) | |
0.4 | 0.193471(15) | |
0.5 | 0.25482(5) | |
0.6 | 0.327098(6) | |
0.7 | 0.413752(14) | |
0.8 | 0.521001(14) | |
0.9 | 0.66408(7) |
In these lattices there may be two percolation thresholds: the lower threshold is the probability above which infinite clusters appear, and the upper is the probability above which there is a unique infinite cluster.
Lattice | z | Site percolation threshold | Bond percolation threshold | |||
---|---|---|---|---|---|---|
Lower | Upper | Lower | Upper | |||
{3,7} hyperbolic | 7 | 7 | 0.26931171(7), [255] 0.20 [256] | 0.73068829(7), [255] 0.73(2) [256] | 0.20, [257] 0.1993505(5) [255] | 0.37, [257] 0.4694754(8) [255] |
{3,8} hyperbolic | 8 | 8 | 0.20878618(9) [255] | 0.79121382(9) [255] | 0.1601555(2) [255] | 0.4863559(6) [255] |
{3,9} hyperbolic | 9 | 9 | 0.1715770(1) [255] | 0.8284230(1) [255] | 0.1355661(4) [255] | 0.4932908(1) [255] |
{4,5} hyperbolic | 5 | 5 | 0.29890539(6) [255] | 0.8266384(5) [255] | 0.27, [257] 0.2689195(3) [255] | 0.52, [257] 0.6487772(3) [255] |
{4,6} hyperbolic | 6 | 6 | 0.22330172(3) [255] | 0.87290362(7) [255] | 0.20714787(9) [255] | 0.6610951(2) [255] |
{4,7} hyperbolic | 7 | 7 | 0.17979594(1) [255] | 0.89897645(3) [255] | 0.17004767(3) [255] | 0.66473420(4) [255] |
{4,8} hyperbolic | 8 | 8 | 0.151035321(9) [255] | 0.91607962(7) [255] | 0.14467876(3) [255] | 0.66597370(3) [255] |
{4,9} hyperbolic | 8 | 8 | 0.13045681(3) [255] | 0.92820305(3) [255] | 0.1260724(1) [255] | 0.66641596(2) [255] |
{5,5} hyperbolic | 5 | 5 | 0.26186660(5) [255] | 0.89883342(7) [255] | 0.263(10), [258] 0.25416087(3) [255] | 0.749(10) [258] 0.74583913(3) [255] |
{7,3} hyperbolic | 3 | 3 | 0.54710885(10) [255] | 0.8550371(5), [255] 0.86(2) [256] | 0.53, [257] 0.551(10), [258] 0.5305246(8) [255] | 0.72, [257] 0.810(10), [258] 0.8006495(5) [255] |
{∞,3} Cayley tree | 3 | 3 | 1⁄2 | 1⁄2 [257] | 1 [257] | |
Enhanced binary tree (EBT) | 0.304(1), [259] 0.306(10), [258] (√13 − 3)/2 = 0.302776 [260] | 0.48, [257] 0.564(1), [259] 0.564(10), [258] 1⁄2 [260] | ||||
Enhanced binary tree dual | 0.436(1), [259] 0.452(10) [258] | 0.696(1), [259] 0.699(10) [258] | ||||
Non-Planar Hanoi Network (HN-NP) | 0.319445 [254] | 0.381996 [254] | ||||
Cayley tree with grandparents | 8 | 0.158656326 [261] | ||||
Note: {m,n} is the Schläfli symbol, signifying a hyperbolic lattice in which n regular m-gons meet at every vertex
For bond percolation on {P,Q}, we have by duality . For site percolation, because of the self-matching of triangulated lattices.
Cayley tree (Bethe lattice) with coordination number
Lattice | z | Site percolation threshold | Bond percolation threshold |
---|---|---|---|
(1+1)-d honeycomb | 1.5 | 0.8399316(2), [262] 0.839933(5), [263] of (1+1)-d sq. | 0.8228569(2), [262] 0.82285680(6) [262] |
(1+1)-d kagome | 2 | 0.7369317(2), [262] 0.73693182(4) [264] | 0.6589689(2), [262] 0.65896910(8) [262] |
(1+1)-d square, diagonal | 2 | 0.705489(4), [265] 0.705489(4), [266] 0.70548522(4), [267] 0.70548515(20), [264] 0.7054852(3), [262] | 0.644701(2), [268] 0.644701(1), [269] 0.644701(1), [265] 0.6447006(10), [263] 0.64470015(5), [270] 0.644700185(5), [267] 0.6447001(2), [262] 0.643(2) [271] |
(1+1)-d triangular | 3 | 0.595646(3), [265] 0.5956468(5), [270] 0.5956470(3) [262] | 0.478018(2), [265] 0.478025(1), [270] 0.4780250(4) [262] 0.479(3) [271] |
(2+1)-d simple cubic, diagonal planes | 3 | 0.43531(1), [272] 0.43531411(10) [262] | 0.382223(7), [272] 0.38222462(6) [262] 0.383(3) [271] |
(2+1)-d square nn (= bcc) | 4 | 0.3445736(3), [273] 0.344575(15) [274] 0.3445740(2) [262] | 0.2873383(1), [275] 0.287338(3) [272] 0.28733838(4) [262] 0.287(3) [271] |
(2+1)-d fcc | 0.199(2)) [271] | ||
(3+1)-d hypercubic, diagonal | 4 | 0.3025(10), [276] 0.30339538(5) [262] | 0.26835628(5), [262] 0.2682(2) [271] |
(3+1)-d cubic, nn | 6 | 0.2081040(4) [273] | 0.1774970(5) [171] |
(3+1)-d bcc | 8 | 0.160950(30), [274] 0.16096128(3) [262] | 0.13237417(2) [262] |
(4+1)-d hypercubic, diagonal | 5 | 0.23104686(3) [262] | 0.20791816(2), [262] 0.2085(2) [271] |
(4+1)-d hypercubic, nn | 8 | 0.1461593(2), [273] 0.1461582(3) [277] | 0.1288557(5) [171] |
(4+1)-d bcc | 16 | 0.075582(17), [274] 0.0755850(3), [277] 0.07558515(1) [262] | 0.063763395(5) [262] |
(5+1)-d hypercubic, diagonal | 6 | 0.18651358(2) [262] | 0.170615155(5), [262] 0.1714(1) [271] |
(5+1)-d hypercubic, nn | 10 | 0.1123373(2) [273] | 0.1016796(5) [171] |
(5+1)-d hypercubic bcc | 32 | 0.035967(23), [274] 0.035972540(3) [262] | 0.0314566318(5) [262] |
(6+1)-d hypercubic, diagonal | 7 | 0.15654718(1) [262] | 0.145089946(3), [262] 0.1458 [271] |
(6+1)-d hypercubic, nn | 12 | 0.0913087(2) [273] | 0.0841997(14) [171] |
(6+1)-d hypercubic bcc | 64 | 0.017333051(2) [262] | 0.01565938296(10) [262] |
(7+1)-d hypercubic, diagonal | 8 | 0.135004176(10) [262] | 0.126387509(3), [262] 0.1270(1) [271] |
(7+1)-d hypercubic,nn | 14 | 0.07699336(7) [273] | 0.07195(5) [171] |
(7+1)-d bcc | 128 | 0.008 432 989(2) [262] | 0.007 818 371 82(6) [262] |
nn = nearest neighbors. For a (d + 1)-dimensional hypercubic system, the hypercube is in d dimensions and the time direction points to the 2D nearest neighbors.
Lattice | z | Site percolation threshold | Bond percolation threshold |
---|---|---|---|
(1+1)-d square with 3 NN | 3 | 0.4395(3), [278] |
p_b = bond threshold
p_s = site threshold
Site-bond percolation is equivalent to having different probabilities of connections:
P_0 = probability that no sites are connected
P_2 = probability that exactly one descendant is connected to the upper vertex (two connected together)
P_3 = probability that both descendants are connected to the original vertex (all three connected together)
Formulas:
P_0 = (1-p_s) + p_s(1-p_b)^2
P_2 = p_s p_b (1-p_b)
P_3 = p_s p_b^2
P_0 + 2P_2 + P_3 = 1
Lattice | z | p_s | p_b | P_0 | P_2 | P_3 |
---|---|---|---|---|---|---|
(1+1)-d square [279] | 3 | 0.644701 | 1 | 0.126237 | 0.229062 | 0.415639 |
0.7 | 0.93585 | 0.148376 | 0.196529 | 0.458567 | ||
0.75 | 0.88565 | 0.169703 | 0.166059 | 0.498178 | ||
0.8 | 0.84135 | 0.192304 | 0.134616 | 0.538464 | ||
0.85 | 0.80190 | 0.216143 | 0.102242 | 0.579373 | ||
0.9 | 0.76645 | 0.241215 | 0.068981 | 0.620825 | ||
0.95 | 0.73450 | 0.267336 | 0.034889 | 0.662886 | ||
1 | 0.705489 | 0.294511 | 0 | 0.705489 | ||
Inhomogeneous triangular lattice bond percolation [20]
Inhomogeneous honeycomb lattice bond percolation = kagome lattice site percolation [20]
Inhomogeneous (3,12^2) lattice, site percolation [7] [280]
or
Inhomogeneous union-jack lattice, site percolation with probabilities [281]
Inhomogeneous martini lattice, bond percolation [73] [282]
Inhomogeneous martini lattice, site percolation. r = site in the star
Inhomogeneous martini-A (3–7) lattice, bond percolation. Left side (top of "A" to bottom): . Right side: . Cross bond: .
Inhomogeneous martini-B (3–5) lattice, bond percolation
Inhomogeneous martini lattice with outside enclosing triangle of bonds, probabilities from inside to outside, bond percolation [282]
Inhomogeneous checkerboard lattice, bond percolation [57] [93]
Inhomogeneous bow-tie lattice, bond percolation [56] [93]
where are the four bonds around the square and is the diagonal bond connecting the vertex between bonds and .
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In the study of complex networks, a network is said to have community structure if the nodes of the network can be easily grouped into sets of nodes such that each set of nodes is densely connected internally. In the particular case of non-overlapping community finding, this implies that the network divides naturally into groups of nodes with dense connections internally and sparser connections between groups. But overlapping communities are also allowed. The more general definition is based on the principle that pairs of nodes are more likely to be connected if they are both members of the same community(ies), and less likely to be connected if they do not share communities. A related but different problem is community search, where the goal is to find a community that a certain vertex belongs to.
In quantum information and quantum computing, a cluster state is a type of highly entangled state of multiple qubits. Cluster states are generated in lattices of qubits with Ising type interactions. A cluster C is a connected subset of a d-dimensional lattice, and a cluster state is a pure state of the qubits located on C. They are different from other types of entangled states such as GHZ states or W states in that it is more difficult to eliminate quantum entanglement in the case of cluster states. Another way of thinking of cluster states is as a particular instance of graph states, where the underlying graph is a connected subset of a d-dimensional lattice. Cluster states are especially useful in the context of the one-way quantum computer. For a comprehensible introduction to the topic see.
In particle physics, hexaquarks, alternatively known as sexaquarks, are a large family of hypothetical particles, each particle consisting of six quarks or antiquarks of any flavours. Six constituent quarks in any of several combinations could yield a colour charge of zero; for example a hexaquark might contain either six quarks, resembling two baryons bound together, or three quarks and three antiquarks. Once formed, dibaryons are predicted to be fairly stable by the standards of particle physics.
In the context of the physical and mathematical theory of percolation, a percolation transition is characterized by a set of universal critical exponents, which describe the fractal properties of the percolating medium at large scales and sufficiently close to the transition. The exponents are universal in the sense that they only depend on the type of percolation model and on the space dimension. They are expected to not depend on microscopic details such as the lattice structure, or whether site or bond percolation is considered. This article deals with the critical exponents of random percolation.
Classic epidemic models of disease transmission are described in Compartmental models in epidemiology. Here we discuss the behavior when such models are simulated on a lattice. Lattice models, which were first explored in the context of cellular automata, act as good first approximations of more complex spatial configurations, although they do not reflect the heterogeneity of space. Lattice-based epidemic models can also be implemented as fixed agent-based models.
The SP formula for the dephasing rate of a particle that moves in a fluctuating environment unifies various results that have been obtained, notably in condensed matter physics, with regard to the motion of electrons in a metal. The general case requires to take into account not only the temporal correlations but also the spatial correlations of the environmental fluctuations. These can be characterized by the spectral form factor , while the motion of the particle is characterized by its power spectrum . Consequently, at finite temperature the expression for the dephasing rate takes the following form that involves S and P functions:
In strong interaction physics, light front holography or light front holographic QCD is an approximate version of the theory of quantum chromodynamics (QCD) which results from mapping the gauge theory of QCD to a higher-dimensional anti-de Sitter space (AdS) inspired by the AdS/CFT correspondence proposed for string theory. This procedure makes it possible to find analytic solutions in situations where strong coupling occurs, improving predictions of the masses of hadrons and their internal structure revealed by high-energy accelerator experiments. The most widely used approach to finding approximate solutions to the QCD equations, lattice QCD, has had many successful applications; It is a numerical approach formulated in Euclidean space rather than physical Minkowski space-time.
The toric code is a topological quantum error correcting code, and an example of a stabilizer code, defined on a two-dimensional spin lattice. It is the simplest and most well studied of the quantum double models. It is also the simplest example of topological order—Z2 topological order (first studied in the context of Z2 spin liquid in 1991). The toric code can also be considered to be a Z2 lattice gauge theory in a particular limit. It was introduced by Alexei Kitaev.
Water retention on random surfaces is the simulation of catching of water in ponds on a surface of cells of various heights on a regular array such as a square lattice, where water is rained down on every cell in the system. The boundaries of the system are open and allow water to flow out. Water will be trapped in ponds, and eventually all ponds will fill to their maximum height, with any additional water flowing over spillways and out the boundaries of the system. The problem is to find the amount of water trapped or retained for a given surface. This has been studied extensively for random surfaces.
Double ionization is a process of formation of doubly charged ions when laser radiation is exerted on neutral atoms or molecules. Double ionization is usually less probable than single-electron ionization. Two types of double ionization are distinguished: sequential and non-sequential.
The Jaynes–Cummings–Hubbard (JCH) model is a many-body quantum system modeling the quantum phase transition of light. As the name suggests, the Jaynes–Cummings–Hubbard model is a variant on the Jaynes–Cummings model; a one-dimensional JCH model consists of a chain of N coupled single-mode cavities, each with a two-level atom. Unlike in the competing Bose–Hubbard model, Jaynes–Cummings–Hubbard dynamics depend on photonic and atomic degrees of freedom and hence require strong-coupling theory for treatment. One method for realizing an experimental model of the system uses circularly-linked superconducting qubits.
Global cascades models are a class of models aiming to model large and rare cascades that are triggered by exogenous perturbations which are relatively small compared with the size of the system. The phenomenon occurs ubiquitously in various systems, like information cascades in social systems, stock market crashes in economic systems, and cascading failure in physics infrastructure networks. The models capture some essential properties of such phenomenon.
Robustness, the ability to withstand failures and perturbations, is a critical attribute of many complex systems including complex networks.
Random sequential adsorption (RSA) refers to a process where particles are randomly introduced in a system, and if they do not overlap any previously adsorbed particle, they adsorb and remain fixed for the rest of the process. RSA can be carried out in computer simulation, in a mathematical analysis, or in experiments. It was first studied by one-dimensional models: the attachment of pendant groups in a polymer chain by Paul Flory, and the car-parking problem by Alfréd Rényi. Other early works include those of Benjamin Widom. In two and higher dimensions many systems have been studied by computer simulation, including in 2d, disks, randomly oriented squares and rectangles, aligned squares and rectangles, various other shapes, etc.