Percolation threshold

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Percolation threshold is a mathematical concept related to percolation theory, which is 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.

Percolation models

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 appears, 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).

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.[1] 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.

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.

The notation such as (4,82) comes from Grünbaum and Shephard,[2] 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.

Thresholds on Archimedean lattices

Example image caption

This is a picture of the 11 Archimedean Lattices or uniform tilings, in which all polygons are regular and each vertex is surrounded by the same sequence of polygons. The notation (34, 6) for example means that every vertex is surrounded by four triangles and one hexagon. Drawings from .[3] See also Uniform Tilings.

    Lattice z \overline z Site Percolation Threshold Bond Percolation Threshold
    3-12 or (3, 122 ) 3 3 0.807900764... = (1 - 2 sin (π/18))1/2[4] 0.7404207988509(8),[5][6] 0.740420800(2),[7] 0.74042195(80),[8] 0.74042077(2)[9]
    cross (4, 6, 12) 3 3 0.7478008(2),[5] 0.747806(4)[4] 0.6937314(1),[5] 0.69373383(72)[8]
    square octagon, bathroom tile, 4-8, truncated square

    (4, 82)

    		 3 3 0.7297232(5),[5] 0.729724(3)[4] 0.6768031269(6),[5] 0.67680232(63),[8] 0.6768 [10]
    honeycomb (63) 3 3 0.6962(6),[11] 0.697040230(5),[5] 0.6970402(1),[12] 0.6970413(10),[13] 0.697043(3),[4] 0.652703645... = 1-2 sin (π/18), 1+ p3-3p2=0[14]
    kagome (3, 6, 3, 6) 4 4 0.652703645... = 1 - 2 sin(π/18)[14] 0.524404978(5),[9] 0.52440499(2),[12] 0.52440572...,[15] 0.52440500(1),[7] 0.52440516(10),[13] 0.5244053(3),[16]

    0.524404999173(3),[5][6] 0.524404999167439(4)[17]
    ruby,[18] rhombitrihexagonal (3, 4, 6, 4) 4 4 0.62181207(7),[5] 0.621819(3)[4] 0.5248311(1),[5] 0.52483258(53)[8]
    square (44) 4 4 0.59274605079210(2),[17] 0.59274601(2),[5] 0.59274605095(15),[19] 0.59274621(13),[20] 0.59274621(33),[21] 0.59274598(4),[22][23] 0.59274605(3),[12] 0.593(1),[24]

    0.591(1),[25] 0.569(13)[26]

    		 1/2
    snub hexagonal, maple leaf [27] (34,6 ) 5 5 0.579498(3)[4] 0.43432764(3),[5] 0.43430621(50)[8]
    snub square, puzzle (32, 4, 3, 4 ) 5 5 0.550806(3)[4] 0.4141378476 (7),[5] 0.41413743(46)[8]
    frieze, (33, 42) 5 5 0.550213(3),[4] 0.5502(8)[28] 0.41964044(1),[5] 0.41964191(43),[8] 0.4196(6) [28]
    triangular (36) 6 6 1/2 0.347296355... = 2 sin (π/18), 1+ p3-3p=0[14]

    Note: sometimes "hexagonal" is used in place of honeycomb, although in some fields, a triangular lattice is also called a hexagonal lattice. z = bulk coordination number.

    Square lattice with complex neighborhoods

    Lattice z Site Percolation Threshold Bond Percolation Threshold
    square: 3N, 4N, 6N 4 0.592...[29][30]
    square: 3N+2N, 4N+3N, 6N+4N 8 0.407...[29][30][31]
    square: 4N+2N 8 0.337...[29][30]
    square: 6N+3N 8 0.337...[30]
    square: 5N 8 0.270...[30]
    square: 6N+2N 8 0.277...[30]
    square: 4N+3N+2N 12 0.288...[29][30]
    square: 6N+4N+3N 12 0.288...[30]
    square: 5N+2N 12 0.236...[30]
    square: 5N+3N 12 0.225...[30]
    square: 5N+4N 12 0.221...[30]
    square: 6N+3N+2N 12 0.240...[30]
    square: 6N+4N+2N 12 0.233...[30]
    square: 6N+5N 12 0.199...[30]
    square: 5N+3N+2N 16 0.219...[30]
    square: 5N+4N+2N 16 0.208...[30]
    square: 5N+4N+3N 16 0.202...[30]
    square: 6N+5N+2N 16 0.187...[30]
    square: 6N+5N+3N 16 0.182...[30]
    square: 6N+5N+4N 16 0.179...[30]
    square: 6N+4N+3N+2N 16 0.208...[30]
    square: 5N+4N+3N+2N 20 0.196...[30] 0.196 724(5)[32]
    square: 6N+5N+3N+2N 20 0.177...[30]
    square: 6N+5N+4N+2N 20 0.172...[30]
    square: 6N+5N+4N+3N 20 0.167...[30]
    square: 6N+5N+4N+3N+2N 24 0.164...[30]

    2N = nearest neighbours, 3N = next-nearest neighbours, 4N = next-next-nearest neighbours, 5N = next-next-next-nearest neighbours, etc.

    Approximate formulas for thresholds of Archimedean lattices

    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 [33]
    honeycomb (63) 3
    kagome (3, 6, 3, 6) 4 0.524430..., 3p2 + 6p3 - 12 p4+ 6 p5 - p6 = 1 [34]
    (3, 4, 6, 4) 4
    square (44) 4 1/2 (exact)
    (34,6 ) 5 0.434371..., 12p3 + 36p4 -21 p5- 327 p6 + 69p7 + 2532p8 - 6533 p9

    + 8256 p10 - 6255p11 + 2951p12 - 837 p13+ 126 p14 - 7p15= 1 [35]
    snub square, puzzle (32, 4, 3, 4 ) 5
    (33, 42) 5
    triangular (36) 6 1/2 (exact)

    Formulas for site-bond percolation

    Lattice z \overline z Threshold Notes
    (63) honeycomb 3 3 b s [1 - (\sqrt{t}/(3-t))(\sqrt{b} - \sqrt{t})] = t ,

    when equal: b = s = 0.82199

    		 approximate formula, s = site prob., b = bond prob., t = 1 - 2 sin (π/18) [13]

    Archimedean Duals (Laves Lattices)

    Example image caption

    Laves lattices are the duals to the Archimedean lattices. Drawings from.[3] See also Uniform Tilings.

    Lattice z \overline z Site Percolation Threshold Bond Percolation Threshold
    Cairo pentagonal

    D(32,4,3,4)=(2/3)(53)+(1/3)(54)

    		 3,4 3⅓ 0.6501834(2),[5] 0.650184(5)[3] 0.585863... = 1-pcbond(32,4,3,4)
    D(33,42)=(1/3)(54)+(2/3)(53) 3,4 3⅓ 0.6470471(2),[5] 0.647084(5)[3] 0.580358... = 1-pcbond(33,42)
    D(34,6)=(1/5)(46)+(4/5)(43) 3,6 3 3/5 0.639447[3] 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),[36] 0.585040(5)[3] 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)[3] 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,[37] 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)[38]

    D(3, 122)=(2/3)(33)+(1/3)(312)

    		 3,12 6 1/2 0.259579... = 1-pcbond(3, 122)

    Site bond percolation (both thresholds apply simultaneously to one system).

    Lattice z \overline z Site Percolation Threshold Bond Percolation Threshold
    square 4 4 0.615185(15)[39] 0.95
    0.667280(15)[39] 0.85
    0.732100(15)[39] 0.75
    0.75 0.726195(15)[39]
    0.815560(15)[39] 0.65
    0.85 0.615810(30)[39]
    0.95 0.533620(15)[39]

    * For more values, see An Investigation of site-bond percolation

    2-Uniform Lattices

    Top 3 Lattices: #13 #12 #36
    Bottom 3 Lattices: #34 #37 #11

    400px

    [2]

    Top 2 Lattices: #35 #30
    Bottom 2 Lattices: #41 #42

    400px

    [2]

    Top 4 Lattices: #22 #23 #21 #20
    Bottom 3 Lattices: #16 #17 #15

    400px

    [2]

    Top 2 Lattices: #31 #32
    Bottom Lattice: #33

    400px

    [2]

    # Lattice z \overline 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)[40] 0.67493252(36)[41]
    42 (1/3)(3,4,6,4) + (2/3)(4,6,12) 4,3 3​1⁄3 0.7157(2)[40] 0.64536587(40)[41]
    36 (1/7)(36) + (6/7)(32,4,12) 6,4 4 ​2⁄7 0.6808(2)[40] 0.55778329(40)[41]
    15 (2/3)(32,62) + (1/3)(3,6,3,6) 4,4 4 0.6499(2)[40] 0.53632487(40)[41]
    34 (1/7)(36) + (6/7)(32,62) 6,4 4 ​2⁄7 0.6329(2)[40] 0.51707873(70)[41]
    16 (4/5)(3,42,6) + (1/5)(3,6,3,6) 4,4 4 0.6286(2)[40] 0.51891529(35)[41]
    17 (4/5)(3,42,6) + (1/5)(3,6,3,6)* 4,4 4 0.6279(2)[40] 0.51769462(35)[41]
    35 (2/3)(3,42,6) + (1/3)(3,4,6,4) 4,4 4 0.6221(2)[40] 0.51973831(40)[41]
    11 (1/2)(34,6) + (1/2)(32,62) 5,4 4.5 0.6171(2)[40] 0.48921280(37)[41]
    37 (1/2)(33,42) + (1/2)(3,4,6,4) 5,4 4.5 0.5885(2)[40] 0.47229486(38)[41]
    30 (1/2)(32,4,3,4) + (1/2)(3,4,6,4) 5,4 4.5 0.5883(2)[40] 0.46573078(72)[41]
    23 (1/2)(33,42) + (1/2)(44) 5,4 4.5 0.5720(2)[40] 0.45844622(40)[41]
    22 (2/3)(33,42) + (1/3)(44) 5,4 4 ​2⁄3 0.5648(2)[40] 0.44528611(40)[41]
    12 (1/4)(36) + (3/4)(34,6) 6,5 5 ​1⁄4 0.5607(2) [40] 0.41109890(37) [41]
    33 (1/2)(33,42) + (1/2)(32,4,3,4) 5,5 5 0.5505(2) [40] 0.41628021(35) [41]
    32 (1/3)(33,42) + (2/3)(32,4,3,4) 5,5 5 0.5504(2) [40] 0.41549285(36) [41]
    31 (1/7)(36) + (6/7)(32,4,3,4) 6,5 5 ​1⁄7 0.5440(2) [40] 0.40379585(40) [41]
    13 (1/2)(36) + (1/2)(34,6) 6,5 5.5 0.5407(2) [40] 0.38914898(35) [41]
    21 (1/3)(36) + (2/3)(33,42) 6,5 5 ​1⁄3 0.5342(2) [40] 0.39491996(40) [41]
    20 (1/2)(36) + (1/2)(33,42) 6,5 5.5 0.5258(2) [40] 0.38285085(38) [41]

    Inhomogeneous 2-Uniform Lattice

    2uniformLattice37

    This figure shows the 2-uniform lattice #37 in the isoradial representation in which each polygon is inscribed in a circle of unit radius. The squares in the 2-uniform lattice must now be represented as rectangles 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 [42] 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.

    Thresholds on 2D bow-tie and martini lattices

    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 2x2, 1x1 subnet for kagome-type lattices (removed).

    Example image caption


    Some other examples of generalized bow-tie lattices (a-d) and the duals of the lattices (e-h)

    Example image caption
    Lattice z \overline z Site Percolation Threshold Bond Percolation Threshold
    martini (3/4)(3,92)+(1/4)(93) 3 3 0.764826..., 1 +p4 - 3p3=0[43] 0.707107... = 1/√2 [44]
    bow-tie (c) 3,4 3 1/7 0.672929..., 1-2p3-2p4-2p5-7p6+18p7+11p8-35p9+21p10-4p11=0 [45]
    bow-tie (d) 3,4 3⅓ 0.625457..., 1-2p2-3p3+4p4-p5=0 [45]
    martini-A (2/3)(3,72)+(1/3)(3,73) 3,4 3⅓ 1/√2[45] 0.625457..., 1-2p2-3p3+4p4-p5=0 [45]
    bow-tie dual lattice (e) 3,4 3⅔ 0.595482..., 1-pcbond (bow-tie (a)) [45]
    bow-tie (b) 3,4,6 3⅔ 0.533213..., 1-p- 2p3 -4p4-4p5+156+ 13p7-36p8+19p9+ p10 + p11=0 [45]
    martini covering/medial (1/2)(33,9)+(1/2)(3,9,3,9) 4 4 0.707107... = 1/√2 [44] 0.57086651(33) [46]
    martini-B (1/2)(3,5,3,52)+(1/2)(3,52) 3, 5 4 0.618034... = 2/(1 +√5)..., 1- p2-p=0[43][45] 1/2 [44][45]
    bow-tie dual lattice (f) 3,4,8 4 2/5 0.466787..., 1-pcbond (bow-tie (b))[45]
    bow-tie (a) (1/2)(32,4,32,4)+(1/2)(3,4,3) 4,6 5 0.5472(2) [28] 0.404518..., 1 - p - 6p2 +6p3-p5=0 [45]
    bow-tie dual lattice (h) 3,6,8 5 0.374543..., 1-pcbond(bow-tie (d))[45]
    bow-tie dual lattice (g) 3,6,10 5½ 0.547... = pcsite(bow-tie(a)) 0.327071..., 1-pcbond(bow-tie (c))[45]

    Thresholds on 2D covering, medial, and matching lattices

    Lattice z \overline z Site Percolation Threshold Bond Percolation Threshold
    (4, 6, 12) covering/medial 4 4 pcbond(4, 6, 12) = 0.693731... 0.5593140(2),[5] 0.559315(1)[47]
    (4, 82) covering/medial, square kagome 4 4 pcbond(4,82) = 0.676803... 0.544798017(4),[5] 0.54479793(34)[47]
    (34, 6) medial 4 4 0.5247495(5)[5]
    (3,4,6,4) medial 4 4 0.51276 [5]
    (32, 4, 3, 4) medial 4 4 0.512682929(8)[5]
    (33, 42) medial 4 4 0.5125245984(9)[5]
    square covering (non-planar) 6 6 1/2 0.3371(1)[48]
    square matching lattice (non-planar) 8 8 1 - pcsite(square) = 0.407253... 0.25036834(6)[12]
    4, 6, 12, Covering/medial lattice

    (4, 6, 12) covering/medial lattice

    (4, 8^2) Covering/medial lattice

    (4, 82) covering/medial lattice

    (3,12^2) Covering/medial lattice

    (3,122) covering/medial lattice (in light grey), equivalent to the kagome (2 x 2) subnet, and in black, the dual of these lattices.

    (3,4,6,4) medial lattice
    (3,4,6,4) medial dual

    (left) (3,4,6,4) covering/medial lattice, (right) (3,4,6,4) medial dual, shown in red, with medial lattice in light gray behind it

    Thresholds on 2D chimera non-planar lattices

    Lattice z \overline z Site Percolation Threshold Bond Percolation Threshold
    K(2,2) 4 4 0.51253(14)[49] 0.44778(15) [49]
    K(3,3) 6 6 0.43760(15) [49] 0.35502(15) [49]
    K(4,4) 8 8 0.38675(7) [49] 0.29427(12) [49]
    K(5,5) 10 10 0.35115(13) [49] 0.25159(13) [49]
    K(6,6) 12 12 0.32232(13)[49] 0.21942(11) [49]
    K(7,7) 14 14 0.30052(14) [49] 0.19475(9) [49]
    K(8,8) 16 16 0.28103(11) [49] 0.17496(10) [49]

    Thresholds on subnet lattices

    Example image caption

    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 [50]

    Lattice z \overline z Site Percolation Threshold Bond Percolation Threshold
    checkerboard – 2 × 2 subnet 4,3 0.596303(1) [51]
    checkerboard – 4 × 4 subnet 4,3 0.633685(9) [51]
    checkerboard – 8 × 8 subnet 4,3 0.642318(5) [51]
    checkerboard – 16 × 16 subnet 4,3 0.64237(1) [51]
    checkerboard- 32 × 32 subnet 4,3 0.64219(2) [51]
    checkerboard – \infty subnet 4,3 0.642216(10) [51]
    kagome – 2 × 2 subnet = (3, 122) covering/medial 4 pcbond (3, 122) = 0.74042077... 0.600861966960(2),[5] 0.6008624(10),[13] 0.60086193(3)[9]
    kagome – 3 × 3 subnet 4 0.6193296(10),[13] 0.61933176(5),[9] 0.61933044(32)[52]
    kagome – 4 × 4 subnet 4 0.625365(3),[13] 0.62536424(7)[9]
    kagome – \infty subnet 4 0.628961(2) [13]
    kagome – (1 × 1):(2 × 2) subnet = martini covering/medial 4 pcbond(martini) = 1/√2 = 0.707107... 0.57086648(36) [46]
    kagome – (1 × 1):(3 × 3) subnet 4,3 0.728355596425196...[9] 0.58609776(37) [52]
    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) [52]
    triangular – 2 × 2 subnet 6,4 0.471628788 [51]
    triangular – 3 × 3 subnet 6,4 0.509077793 [51]
    triangular – 4 × 4 subnet 6,4 0.524364822 [51]
    triangular – 5 × 5 subnet 6,4 0.5315976(10) [51]
    triangular – \infty subnet 6,4 0.53993(1) [51]

    Thresholds of dimers a square lattice

    system z Site Threshold
    unoriented dimers 4 0.5617 [53]
    parallel dimers 4 0.5683[53]

    Thresholds of Full Dimer Coverings of Two Dimensional Lattices

    Here, we are dealing with networks that are obtained by covering a lattice with dimers. 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 [54]
    shifted covering, square lattice 6 0.347296 [54]
    Staggered covering, square lattice 6 0.376825(2) [54]
    Random covering, square lattice 6 0.367713(2) [54]
    parallel covering, triangular lattice 10 0.237418· · · [54]
    Staggered covering, triangular lattice 10 0.237497(2) [54]
    Random covering, triangular lattice 10 0.235340(1) [54]

    Thresholds of polymers (random walks) on a square lattice

    System is composed of ordinary (non-avoiding) random walks of length l on the square lattice. [55]

    l (polymer length) z Bond Percolation
    1 4 0.5(exact) [56]
    2 4 0.47697(4)[56]
    4 4 0.44892(6) [56]
    8 4 0.41880(4)[56]

    Thresholds of self-avoiding walks of length k added by random sequential adsorption

    k z Site Thresholds Bond Thresholds
    1 4 0.593(2) [57] 0.5009(2) [57]
    2 4 0.564(2) [57] 0.4859(2) [57]
    3 4 0.552(2) [57] 0.4732(2) [57]
    4 4 0.542(2) [57] 0.4630(2) [57]
    5 4 0.531(2) [57] 0.4565(2) [57]
    6 4 0.522(2) [57] 0.4497(2) [57]
    7 4 0.511(2) [57] 0.4423(2) [57]
    8 4 0.502(2) [57] 0.4348(2) [57]
    9 4 0.493(2) [57] 0.4291(2) [57]
    10 4 0.488(2) [57] 0.4232(2) [57]
    11 4 0.482(2) [57] 0.4159(2) [57]
    12 4 0.476(2) [57] 0.4114(2) [57]
    13 4 0.471(2) [57] 0.4061(2) [57]
    14 4 0.467(2) [57] 0.4011(2) [57]
    15 4 0.4011(2) [57] 0.3979(2) [57]

    Thresholds on 2D inhomogeneous lattices

    Lattice z Site Percolation Threshold Bond Percolation Threshold
    bow-tie with p = 1/2 on one non-diagonal bond 3 0.3819654(5),[58] (3 - \sqrt{5})/2 [33]

    Thresholds for 2D continuum models

    File:2D continuum percolation with disks.jpg
    2D continuum percolation with disks
    File:2D continuum percolation with ellipses of aspect ratio 2.jpg
    2D continuum percolation with ellipses of aspect ratio 2
    System Φc ηc nc
    Disks of radius r 0.6763475(6),[59] 0.676339(4) [60] 1.12808737(6),[61] 1.128085(2),[59] 1.128059(12) [60] 1.436322(2),[59] 1.436289(16) [60]
    Ellipses, aspect ratio ε = 2 0.63 [62] 0.76 1.94
    Ellipses, ε = 5 0.455 [63] 0.607 3.864
    Ellipses, ε = 10 0.301 [63] 0.358 4.56
    Ellipses, ε = 20 0.178 [63] 0.196 4.99
    Ellipses, ε = 50 0.081 [63] 0.084 5.38
    Ellipses, ε = 100 0.0417 [63] 0.0426 5.42
    Ellipses, ε = 1000 0.0043 [63] 0.00431 5.5
    Aligned squares of side \ell 0.66674349(3),[61] 0.66653(1),[64] 0.6666(4)[65] 1.09884280(9),[61] 1.0982(3),[64] 1.098(1)[65] 1.09884280(9),[61] 1.0982(3),[64] 1.098(1)[65]
    Randomly oriented squares 0.62554075(4),[61] 0.6254(2)[65] 0.9822723(1),[61] 0.9819(6)[65] 0.982278(14) [66] 0.9822723(1),[61] 0.9819(6)[65] 0.982278(14) [66]
    Rectangles, ε = 1.1 0.624870(7) 0.980484(19) 1.078532(21) [66]
    Rectangles, ε = 2 0.590635(5) 0.893147(13) 1.786294(26) [66]
    Rectangles, ε = 3 0.5405983(34) 0.777830(7) 2.333491(22) [66]
    Rectangles, ε = 4 0.4948145(38) 0.682830(8) 2.731318(30) [66]
    Rectangles, ε = 5 0.4551398(31) 0.607226(6) 3.036130(28) [66]
    Rectangles, ε = 10 0.3233507(25) 0.3906022(37) 3.906022(37) [66]
    Rectangles, ε = 20 0.2048518(22) 0.2292268(27) 4.584535(54) [66]
    Rectangles, ε = 50 0.09785513(36) 0.1029802(4) 5.149008(20) [66]
    Rectangles, ε = 100 0.0523676(6) 0.0537886(6) 5.378856(60) [66]
    Rectangles, ε = 200 0.02714526(34) 0.02752050(35) 5.504099(69) [66]
    Rectangles, ε = 1000 0.00559424(6) 0.00560995(6) 5.609947(60) [66]
    Sticks of length \ell 5.6372858(6),[61] 5.63726(2) [67]
    Power-law disks, x=2.05 0.993(1) [68] 4.90(1) 0.0380(6)
    Power-law disks, x=2.25 0.8591(5) [68] 1.959(5) 0.06930(12)
    Power-law disks, x=2.5 0.7836(4) [68] 1.5307(17) 0.09745(11)
    Power-law disks, x=4 0.69543(6) [68] 1.18853(19) 0.18916(3)
    Power-law disks, x=5 0.68643(13) [68] 1.1597(3) 0.22149(8)
    Power-law disks, x=6 0.68241(8) [68] 1.1470(1) 0.24340(5)
    Power-law disks, x=7 0.6803(8) [68] 1.140(6) 0.25933(16)
    Power-law disks, x=8 0.67917(9) [68] 1.1368(5) 0.27140(7)
    Power-law disks, x=9 0.67856(12) [68] 1.1349(4) 0.28098(9)
    Voids around disks of radius r 1 - Φc(disk) = 0.32355169(2),[61] 0.318(2),[69] 0.3261(6)[70]

    \eta_c = \pi r^2 N / L^2 equals critical total area for disks, where N is the number of objects and L is the system size.

    \eta_c = \pi a b N / L^2 for ellipses of semi-major and semi-minor axes of a and b, respectively. Aspect ratio \epsilon = a / b with a > b.

    \eta_c = \ell m N / L^2 for rectangles of dimensions \ell and m. Aspect ratio \epsilon = \ell/m with \ell > m.

    \eta_c = \pi x N / (4 L^2 (x-2)) for power-law distributed disks with \hbox{Prob(radius}\ge R) = R^{-x}, R \ge 1 .

    \phi_c = 1 - e^{-\eta_c} equals critical area fraction.

    n_c = \ell^2 N / L^2 equals number of objects of maximum length \ell = 2 a per unit area.

    For ellipses, n_c = (4 \epsilon / \pi)\eta_c

    For void percolation, \phi_c = e^{-\eta_c} is the critical void fraction.

    For more ellipse values, see [62]

    For more rectangle values, see [66]

    Thresholds on 2D random and quasi-lattices

    File:VoronoiDelaunay.svg
    Voronoi diagram (solid lines) and its dual, the Delaunay triangulation (dotted lines), for a Poisson distribution of points
    File:Voronoi.png
    Delaunay triangulation
    File:VoronoiCov12.png
    The Voronoi covering or line graph (dotted red lines) and the Voronoi diagram (black lines)
    File:RNGonDelaunayTriangulation128vertices.jpg
    The Relative Neighborhood Graph (black lines) [71] superimposed on the Delaunay triangulation (black plus grey lines).
    File:Gabriel Graph.png
    The Gabriel Graph, a subgraph of the Delaunay triangulation in which the circle surrounding each edge does not enclose any other points of the graph
    Lattice z \overline z Site Percolation Threshold Bond Percolation Threshold
    Relative neighborhood graph 2.5576 0.796(2) [71] 0.771(2) [71]
    Voronoi tessellation 3 0.71410(2),[72] 0.7151* [40] 0.68,[73] 0.666931(5),[72] 0.6670(1) [74]
    Voronoi covering/medial 4 0.666931(2)[72][74] 0.53618(2) [72]
    Randomized kagome/square-octagon, fraction r=1/2 4 0.6599[10]
    Penrose rhomb dual 4 0.6381(3)[36] 0.5233(2) [36]
    Gabriel graph 4 0.6348(8),[75] 0.62[76] 0.5167(6),[75] 0.52[76]
    Random-line tessellation, dual 4 0.586(2)[77]
    Penrose rhomb 4 0.5837(3),[36] 0.58391(1)[78] 0.4770(2) [36]
    Octagonal lattice, "chemical" links (Ammann Beenker tiling) 4 0.585 [79] 0.48 [79]
    Octagonal lattice, "ferromagnetic" links 5.17 0.543 [79] 0.40 [79]
    Dodecagonal lattice, "chemical" links 3.63 0.628 [79] 0.54 [79]
    Dodecagonal lattice, "ferromagnetic" links 4.27 0.617 [79] 0.495 [79]
    Delaunay triangulation 6 1/2 [80] 0.333069(2) [72][74]

    *Theoretical estimate

    Thresholds on slabs

    Lattice z \overline z Site Percolation Threshold 0.67634831(2),[61] Bond Percolation Threshold
    h= 2, SC, open b.c. 0.47424 [81]
    h = 3, BCC, periodic b.c. 0.21113018(38) [82]
    h = 4, BCC, periodic b.c. 0.20235168(59) [82]
    h= 4, SC, open b.c. 0.3997 [81]
    h = 5, SC, periodic b.c. 0.278102(5) [82]
    h = 6, SC, periodic b.c. 0.272380(2) [82]
    h = 7, SC, periodic b.c. 5,6 5,6 0.3459514(12) [82] 0.268459(1) [82]
    h= 8, SC, open b.c. 0.3557 [81]
    h = 8, SC, periodic b.c. 0.265615(5) [82]

    More for SC open b.c. in Ref.[81]

    h is the thickness of the slab, h x ∞ x ∞.

    Thresholds on 3D lattices

    Lattice z \overline z filling factor* filling fraction* Site Percolation Threshold Bond Percolation Threshold
    (10,3)-a oxide (or site-bond) [83] 2.4 0.748713(22)[83]
    (10,3)-b oxide (or site-bond) [83] 2.4 0.745317(25)[83]
    silicon dioxide (diamond site-bond) [83] 2 ⅔ 0.638683(35)[83]
    (8,3)-a[84] 3 3 0.577962(33)[84] 0.555700(22)[84]
    (10,3)-a[84] 3 3 0.571404(40)[84] 0.551060(37)[84]
    (10,3)-b[84] 3 3 0.565442(40)[84] 0.546694(33)[84]
    cubic oxide (cubic site-bond)[83] 3 0.524652(50)[83]
    ice Ih 4 4 π √3 / 16 = 0.340087 0.147 0.433(11)[85] 0.388(10)[86]
    diamond (Ice Ic) 4 4 π √3 / 16 = 0.340087 0.1462332 0.4299870(4),[87] 0.426(+0.08,-0.02),[88]

    0.4301(4),[89] 0.428(4),[90] 0.425(15),[91] 0.436(12),[85]

    		 0.3895892(5),[87] 0.3893(2),[89]

    0.388(5),[91] 0.388(5) [90] 0.390(11),[86]
    3D kagome 6 0.3895(2) [92]
    pentagonal stack 5⅓ 0.3394(4) [28] 0.2793(4) [28]
    5⅓ 0.3480(4) [28] 0.2853(4) [28]
    honeycomb stack 5 5 0.3701(2) [28] 0.3093(2) [28]
    5 5 0.3840(4) [28] 0.3168(4) [28]
    4 4 0.4560(6) [28] 0.4031(6) [28]
    kagome stack 6 6 0.3346(4) [28] 0.2563(2) [28]
    dice stack 5,8 6 π √3 / 9 = 0.604600 0.2998(4) [28] 0.2378(4) [28]
    bowtie stack 7 7 0.2822(6) [28] 0.2092(4) [28]
    octagonal stack 8 8 0.2524(6) [28] 0.1752(2) [28]
    simple cubic 6 6 π / 6 = 0.5235988 0.1631574 0.307(10) [91] 0.3116077(2),[93] 0.311604(6),[94]

    0.311605(5),[95] 0.311600(5),[96] 0.3116077(4),[97] 0.3116081(13),[98] 0.3116080(4),[99] 0.3116004(35),[100] 0.31160768(15)[87]

    		 0.247(5) [91]

    0.24881182(10),[93] 0.2488125(25),[101] 0.2488126(5) [102]

    		 0.2555(1)[103]
    Stacked triangular / simple hexagonal 8 8 0.26240(5),[104] 0.2625(2),[105] 0.2623(2)[28] 0.18602(2),[104] 0.1859(2) [28]
    bcc 8 8 0.243(10) [91]

    0.2459615(10),[99] 0.2460(3),[106] 0.2464(7),[107] 0.2458(2)[89]

    		 0.178(5) [91]

    0.1802875(10)[102]
    simple cubic with 3NN 8 8 0.2455(1) [108]
    simple cubic with 3NN+4NN 14 14 0.20490(12) [109]
    fcc 12 12 π / (3 √2) = 0.740480 0.147530 0.198(3),[110] 0.1992365(10),[99] 0.19923517(20),[87] 0.1994(2)[89] 0.1201635(10)[102]
    hcp 12 12 π / (3 √2) = 0.740480 0.147545 0.195(5)[91]

    0.1992555(10)[111]

    		 0.1201640(10)[111]

    0.119(2)[91]
    La2-x Srx Cu O4 12 12 0.19927(2) [112]
    simple cubic with 2NN 12 12 0.1991(1) [108]
    BCC+2NN 14 14 0.1686(20)[113] 0.0991(5)[113]
    simple cubic with 2NN+4NN 18 18 0.15950(12)[109]
    simple cubic with NN+4NN 12 12 0.15040(12) [109]
    simple cubic with NN+3NN 14 14 0.1420(1) [108]
    simple cubic with NN+2NN 18 18 0.1372(1),[108] 0.13735(5) [114]
    simple cubic with short-length correlation 6+ 6+ 0.126(1)[115]
    simple cubic with NN+3NN+4NN 20 20 0.11920(12) [109]
    simple cubic with NN+2NN+4NN 24 24 0.11440(12) [109]
    simple cubic with 2NN+3NN+4NN 26 26 0.11330(12) [109]
    simple cubic with 2NN+3NN 20 20 0.1036(1) [108]
    simple cubic with NN+2NN+3NN+4NN 32 32 0.10000(12) [109]
    simple cubic with NN+2NN+3NN 26 26 0.0976(1),[108] 0.0976445(10) [114]

    Filling factor = fraction of space filled by touching spheres at every lattice site (for systems with uniform bond length only).

    Filling fraction (or Critical Filling Fraction) = filling factor * pc(site).

    NN = nearest neighbor, 2NN = next-nearest neighbor, 3NN = next-next-nearest neighbor, etc.

    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 [116]

    System polymer Φc
    percolating excluded volume of athermal polymer matrix (bond-fluctuation model on cubic lattice) 0.4304(3) [117]

    Thresholds for 3D continuum models

    All overlapping except for jammed spheres and polymer matrix.

    System Φc ηc
    Spheres of radius r 0.2895(5),[118] 0.289573(2),[119] 0.2854 [120] 0.3418(7),[118] 0.341889(3),[119] 0.3360,[120]

    0.34189(2),[64] [corrected]
    Oblate ellipsoids with major radius r and aspect ratio 4/3 0.2831 [120] 0.3328[120]
    Prolate ellipsoids with minor radius r and aspect ratio 3/2 0.2795 [120] 0.3278[120]
    Oblate ellipsoids with major radius r and aspect ratio 2 0.2629 [120] 0.3050[120]
    Prolate ellipsoids with minor radius r and aspect ratio 2 0.2618,[120] 0.25(2)[121] 0.3035,[120] 0.29(3) [121]
    Oblate ellipsoids with major radius r and aspect ratio 3 0.2289 [120] 0.2599[120]
    Prolate ellipsoids with minor radius r and aspect ratio 3 0.2244,[120] 0.20(2)[121] 0.2541,[120] 0.22(3)[121]
    Oblate ellipsoids with major radius r and aspect ratio 4 0.2003 [120] 0.2235[120]
    Prolate ellipsoids with minor radius r and aspect ratio 4 0.1901,[120] 0.16(2)[121] 0.2108,[120] 0.17(3)[121]
    Oblate ellipsoids with major radius r and aspect ratio 5 0.1757 [120] 0.1932[120]
    Prolate ellipsoids with minor radius r and aspect ratio 5 0.1627,[120] 0.13(2)[121] 0.1776,[120] 0.15(2)[121]
    Oblate ellipsoids with major radius r and aspect ratio 10 0.1058 [120] 0.1118[120]
    Prolate ellipsoids with minor radius r and aspect ratio 10 0.08703,[120] 0.07(2)[121] 0.09105,[120] 0.07(2)[121]
    Oblate ellipsoids with major radius r and aspect ratio 100 0.01248[120] 0.01256[120]
    Prolate ellipsoids with minor radius r and aspect ratio 100 0.006949[120] 0.006973[120]
    Oblate ellipsoids with major radius r and aspect ratio 1000 0.001275 [120] 0.001276 [120]
    Oblate ellipsoids with major radius r and aspect ratio 2000 0.000637[120] 0.000637 [120]
    Aligned cylinders 0.2819(2)[122] 0.3312(1)[122]
    Aligned cubes of side \ell = 2 a 0.2773(2) [65] 0.27727(2)[32] 0.3247(3),[64] 0.3248(3)[65]
    Randomly oriented icosahedra 0.3030(5) [123]
    Randomly oriented dodecahedra 0.2949(5) [123]
    Randomly oriented octahedra 0.2514(6) [123]
    Randomly oriented cubes of side \ell = 2 a 0.2168(2) [65] 0.2444(3),[65] 0.2443(5)[123]
    Randomly oriented tetrahedra 0.1701(7) [123]
    Randomly oriented disks of radius r (in 3D) 0.9614(5)[124]
    Randomly oriented square plates of side \sqrt{\pi} r 0.8647(6)[124]
    Randomly oriented triangular plates of side \sqrt{2 \pi} /3^{1/4} r 0.7295(6)[124]
    Voids around disks of radius r 22.86(2)[125]
    Voids around oblate ellipsoids of major radius r and aspect ratio 10 15.42(1)[125]
    Voids around oblate ellipsoids of major radius r and aspect ratio 2 6.478(8)[125]
    Voids around spheres of radius r 0.034(7),[126] 0.030(2),[69] 0.0301(3),[127] 0.0294,[128] 0.0300(3) [129] 0.0317(4) [130] 3.506(8),[129] 3.515(6) [125]
    Voids around aligned cubes 0.036(1) [32]
    Jammed spheres (average z = 6) 0.183(3)[131] 0.59(1) [131]

    \eta_c = (4/3) \pi r^3 N / L^3 is the total volume, where N is the number of objects and L is the system size.

    \phi_c = 1 - e^{-\eta_c} is the critical volume fraction.

    For disks and plates, these are effective volumes and volume fractions.

    For void ("Swiss-Cheese" model), \phi_c = e^{-\eta_c} is the critical void fraction.

    For more results on void percolation around ellipsoids and elliptical plates, see.[125]

    For more ellipsoid percolation values see [120]

    Thresholds on 3D random and quasi-lattices

    Lattice z \overline z Site Percolation Threshold Bond Percolation Threshold
    Contact network of packed spheres 6 0.310(5) [131]
    Random-plane tessellation, dual 6 0.290(7) [132]
    Icosahedral Penrose 6 0.285[133] 0.225 [133]
    Penrose w/2 diagonals 6.764 0.271[133] 0.207 [133]
    Penrose w/8 diagonals 12.764 0.188[133] 0.111[133]
    Voronoi network 15.54 0.1453(20) [113] 0.0822(50)[113]

    Continuum models in higher dimensions

    d System Φc ηc
    4 Overlapping hyperspheres 0.1223(4)[64] 0.1304(5) [64]
    4 Overlapping hypercubes 0.1132(5)[64] 0.1201(6) [64]
    4 Voids around hyperspheres 0.00211(2)[70] 6.161(10)[70]
    5 Overlapping hyperspheres 0.05443(7) [64]
    5 Overlapping hypercubes 0.05024(7) [64]
    5 Voids around hyperspheres 1.26(6)x10−4 [70] 8.98(4)[70]
    6 Overlapping hyperspheres 0.02339(5) [64]
    6 Overlapping hypercubes 0.02104(8)[64]
    6 Voids around hyperspheres 8.0(6)x10−6 [70] 11.74(8)[70]

    \eta_c = (\pi^{d/2}/ \Gamma[d/2 + 1]) r^d N / L^d.

    In 4d, \eta_c = (1/2) \pi^2 r^4 N / L^4.

    In 5d, \eta_c = (8/15) \pi^2 r^5 N / L^5.

    In 6d, \eta_c = (1/6) \pi^3 r^6 N / L^6.

    \phi_c = 1 - e^{-\eta_c} is the critical volume fraction.

    For void models, \phi_c = e^{-\eta_c} is the critical void fraction, and \eta_c is the total volume of the overlapping objects

    Thresholds on hypercubic lattices

    d z Site Thresholds Bond Thresholds
    4 8 0.1968861(14),[134] 0.196889(3),[135] 0.196901(5) [136] 0.1601314(13),[134] 0.160130(3),[135] 0.1601310(10) [101]
    5 10 0.1407966(15) [134] 0.118172(1),[134] 0.1181718(3) [101]
    6 12 0.109017(2) [134] 0.0942019(6) [134]
    7 14 0.0889511(9),[134] 0.088939(20) [137] 0.0786752(3) [134]
    8 16 0.0752101(5) [134] 0.06770839(7) [134]
    9 18 0.0652095(3) [134] 0.05949601(5) [134]
    10 20 0.0575930(1) [134] 0.05309258(4) [134]
    11 22 0.05158971(8) [134] 0.04794969(1) [134]
    12 24 0.04673099(6) [134] 0.04372386(1) [134]
    13 26 0.04271508(8) [134] 0.04018762(1) [134]

    Thresholds in higher-dimensional lattices

    d lattice z Site Thresholds Bond Thresholds
    4 diamond 5 0.2978(2)[89]
    4 kagome 8 0.2715(3) [92]
    4 fcc 24 0.0842(3)[89] 0.049(1)[89]
    5 diamond 6 0.2252(3)[89]
    5 kagome 10 0.2084(4) [92]
    5 bcc 32 0.0446(4)[89] 0.033(1)[89]
    5 fcc 40 0.0431(3)[89] 0.026(2)[89]
    6 diamond 7 0.1799(5)[89]
    6 kagome 12 0.1677(7) [92]
    6 fcc 60 0.0252(5)[89]
    6 bcc 64 0.0199(5)[89]

    Thresholds on hyperbolic, hierarchical, and tree lattices

    File:TriangularHyperbolic.jpg
    Visualization of a triangular hyperbolic lattice {3,7} projected on the Poincaré disk [138]
    File:Hn-np.jpg
    Depiction of the non-planar Hanoi network HN-NP [139]
    Lattice z \overline z Site Percolation Threshold Bond Percolation Threshold
    Lower Upper
    {4,5} hyperbolic 5 5 0.27[140] 0.52[140]
    {7,3} hyperbolic 3 3 0.72[140] 0.53[140]
    {3,7} hyperbolic 7 7 0.20[140] 0.37[140]
    {∞,3} Cayley tree 3 3 1/2 1/2[140] 1[140]
    Enhanced binary tree (EBT) 0.304(1)[140] 0.48,[140] 0.564(1)[141]
    Enhanced binary tree dual 0.436(1)[141] 0.696(1)[141]
    Non-Planar Hanoi Network (HN-NP) 0.319445[139] 0.381996[139]
    Cayley tree with grandparents 8 0.158656326[142]

    Note: {m,n} is the Schläfli symbol, signifying a hyperbolic lattice in which n regular m-gons meet at every vertex

    Cayley tree (Bethe latttice) with coordination number z: pc= 1 / (z - 1)

    Cayley tree with a distribution of z with mean \overline z , mean-square \overline{z^2}: pc= \overline z / (\overline{z^2} - \overline z) [143] (site or bond threshold)

    Thresholds for directed percolation

    File:(1+1)D Kagome Lattice.png
    (1+1)D Kagome Lattice
    File:(1+1)D Square Lattice.png
    (1+1)D Square Lattice
    File:(1+1)D Triangular Lattice.png
    (1+1)D Triangular Lattice
    File:(2+1)D SC Lattice.png
    (2+1)D SC Lattice
    File:(2+1)D BCC Lattice.png
    (2+1)D BCC Lattice
    Lattice z Site Percolation Threshold Bond Percolation Threshold
    (1+1)-d honeycomb 1.5 0.8399316(2),[144] 0.839933(5),[145] 0.8228569(2),[144] 0.82285680(6)[144]
    (1+1)-d kagome 2 0.7369317(2),[144] 0.73693182(4)[146] 0.6589689(2),[144] 0.65896910(8)[144]
    (1+1)-d square, diagonal direction 2 0.705489(4),[147] 0.70548522(4),[148] 0.70548515(20),[146]

    0.7054852(3),[144]

    		 0.644701(2),[149] 0.644701(1),[150] 0.64470015(5),[151] 0.644700185(5),[148] 0.6447001(2),[144]
    (1+1)-d triangular 3 0.5956468(5),[151] 0.5956470(3) [144] 0.478025(1),[151] 0.4780250(4) [144]
    (2+1)-d simple cubic, diagonal planes 3 0.43531(1) [152] 0.382223(7) [152]
    (2+1)-d square nn (= bcc) 4 0.3445736(3),[153] 0.344575(15) [154] 0.2873383(1),[155] 0.287338(3)[152]
    (3+1)-d hypercubic, diagonal planes 4 0.3025(10) [156]
    (3+1)-d cubic, nn 6 0.2081040(4) [153] 0.1774970(5) [101]
    (3+1)-d body-centered hypercubic 8 0.160950(30) [154]
    (4+1)-d hypercubic, nn 8 0.1461593(2),[153] 0.1461582(3) [157] 0.1288557(5) [101]
    (4+1)-d body-centered hypercubic 16 0.075582(17) [154]

    0.0755850(3) [157]
    (5+1)-d hypercubic, nn 10 0.1123373(2) [153] 0.1016796(5) [101]
    (5+1)-d body-centered hypercubic 32 0.035967(23) [154]
    (6+1)-d hypercubic, nn 12 0.0913087(2) [153] 0.0841997(14) [101]
    (7+1)-d hypercubic,nn 14 0.07699336(7) [153] 0.07195(5) [101]

    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.

    Exact critical manifolds of inhomogeneous systems

    Inhomogeneous triangular lattice bond percolation[14]

    1 - p_1 - p_2 - p_3 + p_1 p_2 p_3 = 0

    Inhomogeneous honeycomb lattice bond percolation = kagome lattice site percolation[14]

    1 - p_1 p_2 - p_1 p_3 - p_2 p_3+ p_1 p_2 p_3 = 0

    Inhomogeneous (3,12^2) lattice, site percolation[4] [158]

    1 - 3(s_1s_2)^2 + (s_1s_2)^3 = 0, or s_1 s_2 = 1 - 2 \sin(\pi/18)

    Inhomogeneous union-jack lattice, site percolation with probabilities p_1, p_2, p_3, p_4[159]

    p_3 = 1 - p_1; \qquad p_4 = 1 - p_2

    Inhomogeneous martini lattice, bond percolation [45][160] 1 - (p_1 p_2 r_3 + p_2 p_3 r_1 + p_1 p_3 r_2) - (p_1 p_2 r_1 r_2 + p_1 p_3 r_1 r_3 + p_2 p_3 r_2 r_3) + p_1 p_2 p_3 ( r_1 r_2 + r_1 r_3 + r_2 r_3) + r_1 r_2 r_3 (p_1 p_2 + p_1 p_3 + p_2 p_3) - 2 p_1 p_2 p_3 r_1 r_2 r_3 = 0

    Inhomogeneous martini lattice, site percolation. r = site in the star

    1 - r (p_1 p_2 + p_1 p_3 + p_2 p_3 - p_1 p_2 p_3) = 0

    Inhomogeneous martini-A (3–7) lattice, bond percolation. Left side (top of "A" to bottom): r_2,\ p_1. Right side: r_1, \ p_2. Cross bond: \ r_3.

    1 - p_1 r_2 - p_2 r_1 - p_1 p_2 r_3 - p_1 r_1 r_3 - p_2 r_2 r_3 + p_1 p_2 r_1 r_3 + p_1 p_2 r_2 r_3 + p_1 r_1 r_2 r_3+ p_2 r_1 r_2 r_3 - p_1 p_2 r_1 r_2 r_3 = 0

    Inhomogeneous martini-B (3–5) lattice, bond percolation

    Inhomogeneous martini lattice with outside enclosing triangle of bonds, probabilities y, x, z from inside to outside, bond percolation [160] 1 - 3 z + z^3-(1-z^2) [3 x^2 y (1 + y - y^2)(1 + z) + x^3 y^2 (3 - 2 y)(1 + 2 z) ] = 0

    Inhomogeneous checkerboard lattice, bond percolation [34][58]

    1 - (p_1 p_2 + p_1 p_3 + p_1 p_4 + p_2 p_3 + p_2 p_4 + p_3 p_4) + p_1 p_2 p_3 + p_1 p_2 p_4 + p_1 p_3 p_4 + p_2 p_3 p_4 = 0

    Inhomogeneous bow-tie lattice, bond percolation [33][58]

    1 - (p_1 p_2 + p_1 p_3 + p_1 p_4 + p_2 p_3 + p_2 p_4 + p_3 p_4) + p_1 p_2 p_3 + p_1 p_2 p_4 + p_1 p_3 p_4 + p_2 p_3 p_4 + u(1 - p_1 p_2 - p_3 p_4 + p_1 p_2 p_3 p_4) = 0

    where p_1, p_2, p_3, p_4 are the four bonds around the square and u is the diagonal bond connecting the vertex between bonds p_4, p_1 and p_2, p_3.

    Percolation thresholds for graphs

    For random graphs not embedded in space the percolation threshold can be calculated exactly. For example, for random regular graphs where all nodes have the same degree k, pc=1/k. For Erdős–Rényi (ER) graphs with Poissonian degree distribution, pc=1/<k>.[161] The critical threshold was calculated exactly also for a network of interdependent ER networks.[162][163]

    See also

    References

    1. ↑ Lua error in package.lua at line 80: module 'strict' not found.
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    3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Lua error in package.lua at line 80: module 'strict' not found.
    4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 Lua error in package.lua at line 80: module 'strict' not found.
    5. ↑ 5.00 5.01 5.02 5.03 5.04 5.05 5.06 5.07 5.08 5.09 5.10 5.11 5.12 5.13 5.14 5.15 5.16 5.17 5.18 5.19 5.20 5.21 Lua error in package.lua at line 80: module 'strict' not found.
    6. ↑ 6.0 6.1 Lua error in package.lua at line 80: module 'strict' not found.
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    8. ↑ 8.0 8.1 8.2 8.3 8.4 8.5 8.6 Lua error in package.lua at line 80: module 'strict' not found.
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    11. ↑ Lua error in package.lua at line 80: module 'strict' not found.
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    22. ↑ Lua error in package.lua at line 80: module 'strict' not found.
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