Percolation threshold

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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.

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 p_c, 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.

Simply 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,^[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, depending upon the source.

Percolation on 2D lattices[]

Thresholds on Archimedean lattices[]

This is a picture^[3] 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. Some common names that have been given to these lattices are listed in the table below.

Lattice	z	${\displaystyle {\overline {z}}}$	Site percolation threshold	Bond percolation threshold
3-12 or (3, 122 )	3	3	0.807900764... = (1 − 2 sin (π/18))1/2[4]	0.74042195(80),[5] 0.74042077(2)[6] 0.740420800(2),[7] 0.7404207988509(8),[8][9] 0.740420798850811610(2),[10]
cross, truncated trihexagonal (4, 6, 12)	3	3	0.746,[11] 0.750,[12] 0.747806(4),[4] 0.7478008(2)[8]	0.6937314(1),[8] 0.69373383(72),[5] 0.693733124922(2)[10]
square octagon, bathroom tile, 4-8, truncated square (4, 82)	3	-	0.729,[11] 0.729724(3),[4] 0.7297232(5)[8]	0.6768,[13] 0.67680232(63),[5] 0.6768031269(6),[8] 0.6768031243900113(3),[10]
honeycomb (63)	3	3	0.6962(6),[14] 0.697040230(5),[8] 0.6970402(1),[15] 0.6970413(10),[16] 0.697043(3),[4]	0.652703645... = 1-2 sin (π/18), 1+ p3-3p2=0[17]
kagome (3, 6, 3, 6)	4	4	0.652703645... = 1 − 2 sin(π/18)[17]	0.5244053(3),[18] 0.52440516(10),[16] 0.52440499(2),[15] 0.524404978(5),[6] 0.52440572...,[19] 0.52440500(1),[7] 0.524404999173(3),[8][9] 0.524404999167439(4)[20] 0.52440499916744820(1)[10]
ruby,[21] rhombitrihexagonal (3, 4, 6, 4)	4	4	0.620,[11] 0.621819(3),[4] 0.62181207(7)[8]	0.52483258(53),[5] 0.5248311(1),[8] 0.524831461573(1)[10]
square (44)	4	4	0.59274(10),[22] 0.59274605079210(2),[20] 0.59274601(2),[8] 0.59274605095(15),[23] 0.59274621(13),[24] 0.59274621(33),[25] 0.59274598(4),[26][27] 0.59274605(3),[15] 0.593(1),[28] 0.591(1),[29] 0.569(13)[30]	1/2
snub hexagonal, maple leaf[31] (34,6)	5	5	0.579[12] 0.579498(3)[4]	0.43430621(50),[5] 0.43432764(3),[8] 0.4343283172240(6),[10]
snub square, puzzle (32, 4, 3, 4 )	5	5	0.550,[11][32] 0.550806(3)[4]	0.41413743(46),[5] 0.4141378476(7),[8] 0.4141378565917(1),[10]
frieze, elongated triangular(33, 42)	5	5	0.549,[11] 0.550213(3),[4] 0.5502(8)[33]	0.4196(6),[33] 0.41964191(43),[5] 0.41964044(1),[8] 0.41964035886369(2) [10]
triangular (36)	6	6	1/2	0.347296355... = 2 sin (π/18), 1 + p3 − 3p = 0[17]

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.

2d lattices with extended and complex neighborhoods[]

In this section, sq-1,2,3 corresponds to square (NN+2NN+3NN),^[34] etc. Equivalent to square-2N+3N+4N,^[35] sq(1,2,3).^[36] tri = triangular, hc = honeycomb.

Lattice	z	Site percolation threshold	Bond percolation threshold
sq-1, sq-2, sq-3, sq-5	4	0.5927...[34][35] (square site)
sq-1,2, sq-2,3, sq-3,5	8	0.407...[34][35][37] (square matching)	0.25036834(6),[15] 0.2503685,[38] 0.25036840(4) [39]
sq-1,3	8	0.337[34][35]	0.2214995[38]
sq-2,5: 2NN+5NN	8	0.337[35]
hc-1,2,3: honeycomb-NN+2NN+3NN	12	0.300[36]
tri-1,2: triangular-NN+2NN	12	0.295[36]
tri-2,3: triangular-2NN+3NN	12	0.232020(36),[40]
sq-4: square-4NN	8	0.270...[35]
sq-1,5: square-NN+5NN	8 (r ≤ 2)	0.277[35]
sq-1,2,3: square-NN+2NN+3NN	12	0.292,[41] 0.290(5) [42] 0.289,[12] 0.288,[34][35]	0.1522203[38]
sq-2,3,5: square-2NN+3NN+5NN	12	0.288[35]
sq-1,4: square-NN+4NN	12	0.236[35]
sq-2,4: square-2NN+4NN	12	0.225[35]
tri-4: triangular-4NN	12	0.192450(36)[40]
tri-1,2,3: triangular-NN+2NN+3NN	18	0.225,[41] 0.215,[12] 0.215459(36)[40]
sq-3,4: 3NN+4NN	12	0.221[35]
sq-1,2,5: NN+2NN+5NN	12	0.240[35]	0.13805374[38]
sq-1,3,5: NN+3NN+5NN	12	0.233[35]
sq-4,5: 4NN+5NN	12	0.199[35]
sq-1,2,4: NN+2NN+4NN	16	0.219[35]
sq-1,3,4: NN+3NN+4NN	16	0.208[35]
sq-2,3,4: 2NN+3NN+4NN	16	0.202[35]
sq-1,4,5: NN+4NN+5NN	16	0.187[35]
sq-2,4,5: 2NN+4NN+5NN	16	0.182[35]
sq-3,4,5: 3NN+4NN+5NN	16	0.179[35]
sq-1,2,3,5: NN+2NN+3NN+5NN	16	0.208[35]	0.1032177[38]
tri-4,5: 4NN+5NN	18	0.140250(36),[40]
sq-1,2,3,4: NN+2NN+3NN+4NN (r≤${\displaystyle {\sqrt {5}}}$)	20	0.196[35] 0.196724(10)[43]	0.0841509[38]
sq-1,2,4,5: NN+2NN+4NN+5NN	20	0.177[35]
sq-1,3,4,5: NN+3NN+4NN+5NN	20	0.172[35]
sq-2,3,4,5: 2NN+3NN+4NN+5NN	20	0.167[35]
sq-1,2,3,5,6: NN+2NN+3NN+5NN+6NN	20		0.0783110[38]
sq-1,2,3,4,5: NN+2NN+3NN+4NN+5NN (r≤${\displaystyle {\sqrt {8}}}$)	24	0.164[35]
tri-1,4,5: NN+4NN+5NN	24	0.131660(36)[40]
sq-1,...,6: NN+...+6NN (r≤3)	28	0.142[12]	0.0558493[38]
tri-2,3,4,5: 2NN+3NN+4NN+5NN	30	0.117460(36)[40]
tri-1,2,3,4,5: NN+2NN+3NN+4NN+5NN	36	0.115,[12] 0.115740(36)[40]
sq-1,...,7: NN+...+7NN (r≤${\displaystyle {\sqrt {10}}}$)	36	0.113[12]	0.04169608[38]
square: square distance ≤ 4	40	0.105(5)[42]
sq-(1,...,8: NN+..+8NN (r≤${\displaystyle {\sqrt {13}}}$)	44	0.095765(5),[43] 0.095[32]
sq-1,...,9: NN+..+9NN	48	0.086 [12]	0.02974268[38]
sq-1,...,11: NN+...+11NN	60		0.02301190(3)[38]
sq-1,... (r ≤ 7)	148		0.008342595[39]
sq-1,...,32: NN+...+32NN	224		0.0053050415(33)[38]
sq-1,...,86: NN+...+86NN (r≤15)	708		0.001557644(4)[44]
sq-1,...,141: NN+...+141NN (r≤${\displaystyle {\sqrt {389}}}$)	1224		0.000880188(90)[38]
sq-1,...,185: NN+...+185NN (r≤23)	1652		0.000645458(4)[44]
sq-1,...,317: NN+...+317NN (r≤31)	3000		0.000349601(3)[44]
sq-1,...,413: NN+...+413NN (r≤${\displaystyle {\sqrt {1280}}}$)	4016		0.0002594722(11)[38]
square: square distance ≤ 6	84	0.049(5)[42]
square: square distance ≤ 8	144	0.028(5)[42]
square: square distance ≤ 10	220	0.019(5)[42]
2x2 overlapping squares*		0.58365(2) [43]
3x3 overlapping squares*		0.59586(2) [43]

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.^[34]

• For overlapping squares, ${\displaystyle p_{c}}$(site) given here is the net fraction of sites occupied ${\displaystyle \phi _{c}}$ similar to the ${\displaystyle \phi _{c}}$ in continuum percolation. The case of a 2×2 system is equivalent to percolation of a square lattice NN+2NN+3NN+4NN or sq-1,2,3,4 with threshold ${\displaystyle 1-(1-\phi _{c})^{1/4}=0.196724(10)\ldots }$ with ${\displaystyle \phi _{c}=0.58365(2)}$.^[43] The 3×3 system corresponds to sq-1,2,3,4,5,6,7,8 with z=44 and ${\displaystyle p_{c}=1-(1-\phi _{c})^{1/9}=0.095765(5)\ldots }$. For larger overlapping squares, see.^[43]

Approximate formulas for thresholds of Archimedean lattices[]

Site-bond percolation in 2D[]

Site bond percolation. Here ${\displaystyle p_{s}}$ is the site occupation probability and ${\displaystyle p_{b}}$ 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 ${\displaystyle f(p_{s},p_{b})}$ = 0, and some specific critical pairs ${\displaystyle (p_{s},p_{b})}$ are listed below.

Square lattice:

Lattice	z	${\displaystyle {\overline {z}}}$	Site percolation threshold	Bond percolation threshold
square	4	4	0.615185(15)[47]	0.95
			0.667280(15)[47]	0.85
			0.732100(15)[47]	0.75
			0.75	0.726195(15)[47]
			0.815560(15)[47]	0.65
			0.85	0.615810(30)[47]
			0.95	0.533620(15)[47]

Honeycomb (hexagonal) lattice:

Lattice	z	${\displaystyle {\overline {z}}}$	Site percolation threshold	Bond percolation threshold
honeycomb	3	3	0.7275(5)[48]	0.95
			0. 0.7610(5)[48]	0.90
			0.7986(5)[48]	0.85
			0.80	0.8481(5)[48]
			0.8401(5)[48]	0.80
			0.85	0.7890(5)[48]
			0.90	0.7377(5)[48]
			0.95	0.6926(5)[48]

Kagome lattice:

Lattice	z	${\displaystyle {\overline {z}}}$	Site percolation threshold	Bond percolation threshold
kagome	4	4	0.6711(4),[48] 0.67097(3)[49]	0.95
			0.6914(5),[48] 0.69210(2)[49]	0.90
			0.7162(5),[48] 0.71626(3)[49]	0.85
			0.7428(5),[48] 0.74339(3)[49]	0.80
			0.75	0.7894(9)[48]
			0.7757(8),[48] 0.77556(3)[49]	0.75
			0.80	0.7152(7)[48]
			0.81206(3)[49]	0.70
			0.85	0.6556(6)[48]
			0.85519(3)[49]	0.65
			0.90	0.6046(5)[48]
			0.90546(3)[49]	0.60
			0.95	0.5615(4)[48]
			0.96604(4)[49]	0.55
			0.9854(3)[49]	0.53

* For values on different lattices, see An Investigation of site-bond percolation^[48]

Approximate formula for site-bond percolation on a honeycomb lattice

Lattice	z	${\displaystyle {\overline {z}}}$	Threshold	Notes
(63) honeycomb	3	3	${\displaystyle p_{b}p_{s}[1-({\sqrt {p_{bc}}}/(3-p_{bc}))({\sqrt {p_{b}}}-{\sqrt {p_{bc}}})]=p_{bc}}$, When equal: ps = pb = 0.82199	approximate formula, ps = site prob., pb = bond prob., pbc = 1 − 2 sin (π/18),[16] exact at ps=1, pb=pbc.

Archimedean duals (Laves lattices)[]

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

Lattice	z	${\displaystyle {\overline {z}}}$	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),[8] 0.650184(5)[3]	0.585863... = 1 − pcbond(32,4,3,4)
Pentagonal D(33,42)=(1/3)(54)+(2/3)(53)	3,4	3⅓	0.6470471(2),[8] 0.647084(5),[3] 0.6471(6)[33]	0.580358... = 1 − pcbond(33,42), 0.5800(6)[33]
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),[50] 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,[51] 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)[52] D(3, 122)=(2/3)(33)+(1/3)(312)	3,12	6	1/2	0.259579... = 1 − pcbond(3, 122)

2-uniform lattices[]

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

^[2]

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

^[2]

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

^[2]

Top 2 lattices: #31 #32
Bottom lattice: #33

^[2]

#	Lattice	z	${\displaystyle {\overline {z}}}$	Site percolation threshold	Bond percolation threshold
41	(1/2)(3,4,3,12) + (1/2)(3, 122)	4,3	3.5	0.7680(2)[53]	0.67493252(36)[citation needed]
42	(1/3)(3,4,6,4) + (2/3)(4,6,12)	4,3	31⁄3	0.7157(2)[53]	0.64536587(40)[citation needed]
36	(1/7)(36) + (6/7)(32,4,12)	6,4	4 2⁄7	0.6808(2)[53]	0.55778329(40)[citation needed]
15	(2/3)(32,62) + (1/3)(3,6,3,6)	4,4	4	0.6499(2)[53]	0.53632487(40)[citation needed]
34	(1/7)(36) + (6/7)(32,62)	6,4	4 2⁄7	0.6329(2)[53]	0.51707873(70)[citation needed]
16	(4/5)(3,42,6) + (1/5)(3,6,3,6)	4,4	4	0.6286(2)[53]	0.51891529(35)[citation needed]
17	(4/5)(3,42,6) + (1/5)(3,6,3,6)*	4,4	4	0.6279(2)[53]	0.51769462(35)[citation needed]
35	(2/3)(3,42,6) + (1/3)(3,4,6,4)	4,4	4	0.6221(2)[53]	0.51973831(40)[citation needed]
11	(1/2)(34,6) + (1/2)(32,62)	5,4	4.5	0.6171(2)[53]	0.48921280(37)[citation needed]
37	(1/2)(33,42) + (1/2)(3,4,6,4)	5,4	4.5	0.5885(2)[53]	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)[53]	0.46573078(72)[citation needed]
23	(1/2)(33,42) + (1/2)(44)	5,4	4.5	0.5720(2)[53]	0.45844622(40)[citation needed]
22	(2/3)(33,42) + (1/3)(44)	5,4	4 2⁄3	0.5648(2)[53]	0.44528611(40)[citation needed]
12	(1/4)(36) + (3/4)(34,6)	6,5	5 1⁄4	0.5607(2)[53]	0.41109890(37)[citation needed]
33	(1/2)(33,42) + (1/2)(32,4,3,4)	5,5	5	0.5505(2)[53]	0.41628021(35)[citation needed]
32	(1/3)(33,42) + (2/3)(32,4,3,4)	5,5	5	0.5504(2)[53]	0.41549285(36)[citation needed]
31	(1/7)(36) + (6/7)(32,4,3,4)	6,5	5 1⁄7	0.5440(2)[53]	0.40379585(40)[citation needed]
13	(1/2)(36) + (1/2)(34,6)	6,5	5.5	0.5407(2)[53]	0.38914898(35)[citation needed]
21	(1/3)(36) + (2/3)(33,42)	6,5	5 1⁄3	0.5342(2)[53]	0.39491996(40)[citation needed]
20	(1/2)(36) + (1/2)(33,42)	6,5	5.5	0.5258(2)[53]	0.38285085(38)[citation needed]

Inhomogeneous 2-uniform lattice[]

2-uniform lattice #37

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^[54] 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 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	${\displaystyle {\overline {z}}}$	Site percolation threshold	Bond percolation threshold
martini (3/4)(3,92)+(1/4)(93)	3	3	0.764826..., 1 + p4 − 3p3 = 0[55]	0.707107... = 1/√2[56]
bow-tie (c)	3,4	3 1/7		0.672929..., 1 − 2p3 − 2p4 − 2p5 − 7p6 + 18p7 + 11p8 − 35p9 + 21p10 − 4p11 = 0[57]
bow-tie (d)	3,4	3⅓		0.625457..., 1 − 2p2 − 3p3 + 4p4 − p5 = 0[57]
martini-A (2/3)(3,72)+(1/3)(3,73)	3,4	3⅓	1/√2[57]	0.625457..., 1 − 2p2 − 3p3 + 4p4 − p5 = 0[57]
bow-tie dual (e)	3,4	3⅔		0.595482..., 1-pcbond (bow-tie (a))[57]
bow-tie (b)	3,4,6	3⅔		0.533213..., 1 − p − 2p3 -4p4-4p5+156+ 13p7-36p8+19p9+ p10 + p11=0[57]
martini covering/medial (1/2)(33,9) + (1/2)(3,9,3,9)	4	4	0.707107... = 1/√2[56]	0.57086651(33)[citation needed] </ref>
martini-B (1/2)(3,5,3,52) + (1/2)(3,52)	3, 5	4	0.618034... = 2/(1 + √5), 1- p2 − p = 0[55][57]	1/2[56][57]
bow-tie dual (f)	3,4,8	4 2/5		0.466787..., 1 − pcbond (bow-tie (b))[57]
bow-tie (a) (1/2)(32,4,32,4) + (1/2)(3,4,3)	4,6	5	0.5472(2),[33] 0.5479148(7)[58]	0.404518..., 1 − p − 6p2 + 6p3 − p5 = 0[59][57]
bow-tie dual (h)	3,6,8	5		0.374543..., 1 − pcbond(bow-tie (d))[57]
bow-tie dual (g)	3,6,10	5½	0.547... = pcsite(bow-tie(a))	0.327071..., 1 − pcbond(bow-tie (c))[57]
martini dual (1/2)(33) + (1/2)(39)	3,9	6	1/2	0.292893... = 1 − 1/√2[56]

Thresholds on 2D covering, medial, and matching lattices[]

Lattice	z	${\displaystyle {\overline {z}}}$	Site percolation threshold	Bond percolation threshold
(4, 6, 12) covering/medial	4	4	pcbond(4, 6, 12) = 0.693731...	0.5593140(2),[8] 0.559315(1)[citation needed]
(4, 82) covering/medial, square kagome	4	4	pcbond(4,82) = 0.676803...	0.544798017(4),[8] 0.54479793(34)[citation needed]
(34, 6) medial	4	4		0.5247495(5)[8]
(3,4,6,4) medial	4	4		0.51276[8]
(32, 4, 3, 4) medial	4	4		0.512682929(8)[8]
(33, 42) medial	4	4		0.5125245984(9)[8]
square covering (non-planar)	6	6	1/2	0.3371(1)[60]
square matching lattice (non-planar)	8	8	1 − pcsite(square) = 0.407253...	0.25036834(6)[15]

(4, 6, 12) covering/medial lattice

(4, 8²) covering/medial lattice

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

(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. The pattern on the left appears in Iranian tilework ^[61] on the Western tomb tower, Kharraqan.

Thresholds on 2D chimera non-planar lattices[]

Lattice	z	${\displaystyle {\overline {z}}}$	Site percolation threshold	Bond percolation threshold
K(2,2)	4	4	0.51253(14)[62]	0.44778(15)[62]
K(3,3)	6	6	0.43760(15)[62]	0.35502(15)[62]
K(4,4)	8	8	0.38675(7)[62]	0.29427(12)[62]
K(5,5)	10	10	0.35115(13)[62]	0.25159(13)[62]
K(6,6)	12	12	0.32232(13)[62]	0.21942(11)[62]
K(7,7)	14	14	0.30052(14)[62]	0.19475(9)[62]
K(8,8)	16	16	0.28103(11)[62]	0.17496(10)[62]

Thresholds on subnet lattices[]

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.^[63]

Lattice	z	${\displaystyle {\overline {z}}}$	Site percolation threshold	Bond percolation threshold
checkerboard – 2 × 2 subnet	4,3			0.596303(1)[64]
checkerboard – 4 × 4 subnet	4,3			0.633685(9)[64]
checkerboard – 8 × 8 subnet	4,3			0.642318(5)[64]
checkerboard – 16 × 16 subnet	4,3			0.64237(1)[64]
checkerboard – 32 × 32 subnet	4,3			0.64219(2)[64]
checkerboard – ${\displaystyle \infty }$ subnet	4,3			0.642216(10)[64]
kagome – 2 × 2 subnet = (3, 122) covering/medial	4		pcbond (3, 122) = 0.74042077...	0.600861966960(2),[8] 0.6008624(10),[16] 0.60086193(3)[6]
kagome – 3 × 3 subnet	4			0.6193296(10),[16] 0.61933176(5),[6] 0.61933044(32)[citation needed]
kagome – 4 × 4 subnet	4			0.625365(3),[16] 0.62536424(7)[6]
kagome – ${\displaystyle \infty }$ subnet	4			0.628961(2)[16]
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...[6]	0.58609776(37)[citation needed]
kagome – (1 × 1):(4 × 4) subnet			0.738348473943256...[6]
kagome – (1 × 1):(5 × 5) subnet			0.743548682503071...[6]
kagome – (1 × 1):(6 × 6) subnet			0.746418147634282...[6]
kagome – (2 × 2):(3 × 3) subnet				0.61091770(30)[citation needed]
triangular – 2 × 2 subnet	6,4			0.471628788[64]
triangular – 3 × 3 subnet	6,4			0.509077793[64]
triangular – 4 × 4 subnet	6,4			0.524364822[64]
triangular – 5 × 5 subnet	6,4			0.5315976(10)[64]
triangular – ${\displaystyle \infty }$ subnet	6,4			0.53993(1)[64]

Thresholds of random sequentially adsorbed objects[]

(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,[65] 0.6653 [66]
dimers on a triangular lattice	6	0.4872(8),[65] 0.4873,[66] 0.5157(2) [67]
linear 4-mers on a triangular lattice	6	0.5220(2)[67]
linear 8-mers on a triangular lattice	6	0.5281(5)[67]
linear 12-mers on a triangular lattice	6	0.5298(8)[67]
linear 16-mers on a triangular lattice	6	0.5328(7)[67]
linear 32-mers on a triangular lattice	6	0.5407(6)[67]
linear 64-mers on a triangular lattice	6	0.5455(4)[67]
linear 80-mers on a triangular lattice	6	0.5500(6)[67]
linear k ${\displaystyle \longrightarrow \infty }$ on a triangular lattice	6	0.582(9)[67]
dimers and 5% impurities, triangular lattice	6	0.4832(7)[68]
parallel dimers on a square lattice	4	0.5863[69]
dimers on a square lattice	4	0.5617,[69] 0.5618(1),[70] 0.562,[71] 0.5713[66]
linear 3-mers on a square lattice	4	0.528[71]
3-site 120° angle, 5% impurities, triangular lattice	6	0.4574(9)[68]
3-site triangles, 5% impurities, triangular lattice	6	0.5222(9)[68]
linear trimers and 5% impurities, triangular lattice	6	0.4603(8)[68]
linear 4-mers on a square lattice	4	0.504[71]
linear 5-mers on a square lattice	4	0.490[71]
linear 6-mers on a square lattice	4	0.479[71]
linear 8-mers on a square lattice	4	0.474,[71] 0.4697(1)[70]
linear 10-mers on a square lattice	4	0.469[71]
linear 16-mers on a square lattice	4	0.4639(1)[70]
linear 32-mers on a square lattice	4	0.4747(2)[70]

The threshold gives the fraction of sites occupied by the objects when site percolation first takes place (not at full jamming). For longer dimers see Ref.^[72]

Thresholds of full dimer coverings of two dimensional lattices[]

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.

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.^[74]

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

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),[77] ${\displaystyle (3-{\sqrt {5}})/2}$[45]

Thresholds for 2D continuum models[]

2D continuum percolation with disks

2D continuum percolation with ellipses of aspect ratio 2

System	Φc	ηc	nc
Disks of radius r	0.67634831(2),[78] 0.6763475(6),[79] 0.676339(4),[80] 0.6764(4),[81] 0.6766(5),[82] 0.676(2),[83] 0.679,[84] 0.674[85] 0.676,[86] 0.680[87]	1.1276(9),[88] 1.12808737(6),[78] 1.128085(2),[79] 1.128059(12),[80] 1.13,[89] 0.8[90]	1.43632505(10),[91] 1.43632545(8),[78] 1.436322(2),[79] 1.436289(16),[80] 1.436320(4),[92] 1.436323(3),[93] 1.438(2),[94] 1.216 (48)[95]
Ellipses, ε = 1.5	0.0043[84]	0.00431	2.059081(7)[93]
Ellipses, ε = 5/3	0.65[96]	1.05[96]	2.28[96]
Ellipses, aspect ratio ε = 2	0.6287945(12),[93] 0.63[96]	0.991000(3),[93] 0.99[96]	2.523560(8),[93] 2.5[96]
Ellipses, ε = 3	0.56[96]	0.82[96]	3.157339(8),[93] 3.14[96]
Ellipses, ε = 4	0.5[96]	0.69[96]	3.569706(8),[93] 3.5[96]
Ellipses, ε = 5	0.455,[84] 0.455,[86] 0.46[96]	0.607[84]	3.861262(12),[93] 3.86[84]
Ellipses, ε = 6			4.079365(17)[93]
Ellipses, ε = 7			4.249132(16)[93]
Ellipses, ε = 8			4.385302(15)[93]
Ellipses, ε = 9			4.497000(8)[93]
Ellipses, ε = 10	0.301,[84] 0.303,[86] 0.30[96]	0.358[84] 0.36[96]	4.590416(23)[97] 4.56,[84] 4.5[96]
Ellipses, ε = 15			4.894752(30)[93]
Ellipses, ε = 20	0.178,[84] 0.17[96]	0.196[84]	5.062313(39),[93] 4.99[84]
Ellipses, ε = 50	0.081[84]	0.084[84]	5.393863(28),[93] 5.38[84]
Ellipses, ε = 100	0.0417[84]	0.0426[84]	5.513464(40),[93] 5.42[84]
Ellipses, ε = 200	0.021[96]	0.0212[96]	5.40[96]
Ellipses, ε = 1000	0.0043[84]	0.00431	5.624756(22),[93] 5.5
Superellipses, ε = 1, m = 1.5	0.671[86]
Superellipses, ε = 2.5, m = 1.5	0.599[86]
Superellipses, ε = 5, m = 1.5	0.469[86]
Superellipses, ε = 10, m = 1.5	0.322[86]
disco-rectangles, ε = 1.5			1.894 [92]
disco-rectangles, ε = 2			2.245 [92]
Aligned squares of side ${\displaystyle \ell }$	0.66675(2),[43] 0.66674349(3),[78] 0.66653(1),[98] 0.6666(4),[99] 0.668[85]	1.09884280(9),[78] 1.0982(3),[98] 1.098(1)[99]	1.09884280(9),[78] 1.0982(3),[98] 1.098(1)[99]
Randomly oriented squares	0.62554075(4),[78] 0.6254(2)[99] 0.625,[86]	0.9822723(1),[78] 0.9819(6)[99] 0.982278(14)[100]	0.9822723(1),[78] 0.9819(6)[99] 0.982278(14)[100]
Rectangles, ε = 1.1	0.624870(7)	0.980484(19)	1.078532(21)[100]
Rectangles, ε = 2	0.590635(5)	0.893147(13)	1.786294(26)[100]
Rectangles, ε = 3	0.5405983(34)	0.777830(7)	2.333491(22)[100]
Rectangles, ε = 4	0.4948145(38)	0.682830(8)	2.731318(30)[100]
Rectangles, ε = 5	0.4551398(31), 0.451[86]	0.607226(6)	3.036130(28)[100]
Rectangles, ε = 10	0.3233507(25), 0.319[86]	0.3906022(37)	3.906022(37)[100]
Rectangles, ε = 20	0.2048518(22)	0.2292268(27)	4.584535(54)[100]
Rectangles, ε = 50	0.09785513(36)	0.1029802(4)	5.149008(20)[100]
Rectangles, ε = 100	0.0523676(6)	0.0537886(6)	5.378856(60)[100]
Rectangles, ε = 200	0.02714526(34)	0.02752050(35)	5.504099(69)[100]
Rectangles, ε = 1000	0.00559424(6)	0.00560995(6)	5.609947(60)[100]
Sticks of length ${\displaystyle \ell }$			5.6372858(6),[78] 5.63726(2),[101] 5.63724(18) [102]
Power-law disks, x=2.05	0.993(1)[103]	4.90(1)	0.0380(6)
Power-law disks, x=2.25	0.8591(5)[103]	1.959(5)	0.06930(12)
Power-law disks, x = 2.5	0.7836(4)[103]	1.5307(17)	0.09745(11)
Power-law disks, x = 4	0.69543(6)[103]	1.18853(19)	0.18916(3)
Power-law disks, x = 5	0.68643(13)[103]	1.1597(3)	0.22149(8)
Power-law disks, x = 6	0.68241(8)[103]	1.1470(1)	0.24340(5)
Power-law disks, x=7	0.6803(8)[103]	1.140(6)	0.25933(16)
Power-law disks, x=8	0.67917(9)[103]	1.1368(5)	0.27140(7)
Power-law disks, x = 9	0.67856(12)[103]	1.1349(4)	0.28098(9)
Voids around disks of radius r	1 − Φc(disk) = 0.32355169(2),[78] 0.318(2),[104] 0.3261(6)[105]

${\displaystyle \eta _{c}=\pi r^{2}N/L^{2}}$ equals critical total area for disks, where N is the number of objects and L is the system size.

${\displaystyle 4\eta _{c}}$ gives the number of disk centers within the circle of influence (radius 2 r).

${\displaystyle r_{c}=L{\sqrt {\frac {\eta _{c}}{\pi N}}}}$ is the critical disk radius.

${\displaystyle \eta _{c}=\pi abN/L^{2}}$ for ellipses of semi-major and semi-minor axes of a and b, respectively. Aspect ratio ${\displaystyle \epsilon =a/b}$ with ${\displaystyle a>b}$.

${\displaystyle \eta _{c}=\ell mN/L^{2}}$ for rectangles of dimensions ${\displaystyle \ell }$ and ${\displaystyle m}$. Aspect ratio ${\displaystyle \epsilon =\ell /m}$ with ${\displaystyle \ell >m}$.

${\displaystyle \eta _{c}=\pi xN/(4L^{2}(x-2))}$ for power-law distributed disks with ${\displaystyle {\hbox{Prob(radius}}\geq R)=R^{-x}}$, ${\displaystyle R\geq 1}$.

${\displaystyle \phi _{c}=1-e^{-\eta _{c}}}$ equals critical area fraction.

${\displaystyle n_{c}=\ell ^{2}N/L^{2}}$ equals number of objects of maximum length ${\displaystyle \ell =2a}$ per unit area.

For ellipses, ${\displaystyle n_{c}=(4\epsilon /\pi )\eta _{c}}$

For void percolation, ${\displaystyle \phi _{c}=e^{-\eta _{c}}}$ is the critical void fraction.

For more ellipse values, see ^[96][93]

For more rectangle values, see ^[100]

Both ellipses and rectangles belong to the superellipses, with ${\displaystyle |x/a|^{2m}+|y/b|^{2m}=1}$. For more percolation values of superellipses, see.^[86]

For the monodisperse particle systems, the percolation thresholds of concave-shaped superdisks are obtained as seen in ^[106]

For binary dispersions of disks, see ^{[107][79][108]}

Thresholds on 2D random and quasi-lattices[]

Voronoi diagram (solid lines) and its dual, the Delaunay triangulation (dotted lines), for a Poisson distribution of points

Delaunay triangulation

The Voronoi covering or line graph (dotted red lines) and the Voronoi diagram (black lines)

The Relative Neighborhood Graph (black lines)^[109] superimposed on the Delaunay triangulation (black plus grey lines).

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

Uniform Infinite Planar Triangulation, showing bond clusters. From^[110]

Lattice	z	${\displaystyle {\overline {z}}}$	Site percolation threshold	Bond percolation threshold
Relative neighborhood graph		2.5576	0.796(2)[109]	0.771(2)[109]
Voronoi tessellation	3		0.71410(2),[111] 0.7151*[53]	0.68,[112] 0.6670(1),[113] 0.6680(5),[114] 0.666931(5)[111]
Voronoi covering/medial	4		0.666931(2)[111][113]	0.53618(2)[111]
Randomized kagome/square-octagon, fraction r=1/2	4		0.6599[13]
Penrose rhomb dual	4		0.6381(3)[50]	0.5233(2)[50]
Gabriel graph		4	0.6348(8),[115] 0.62[116]	0.5167(6),[115] 0.52[116]
Random-line tessellation, dual		4	0.586(2)[117]
Penrose rhomb		4	0.5837(3),[50] 0.0.5610(6) (weighted bonds)[118] 0.58391(1)[119]	0.483(5),[120] 0.4770(2)[50]
Octagonal lattice, "chemical" links (Ammann–Beenker tiling)		4	0.585[121]	0.48[121]
Octagonal lattice, "ferromagnetic" links		5.17	0.543[121]	0.40[121]
Dodecagonal lattice, "chemical" links		3.63	0.628[121]	0.54[121]
Dodecagonal lattice, "ferromagnetic" links		4.27	0.617[121]	0.495[121]
Delaunay triangulation		6	1/2[122]	0.3333(1)[113] 0.3326(5),[114] 0.333069(2)[111]
Uniform Infinite Planar Triangulation[123]		6	1/2	(2√3 – 1)/11 ≈ 0.2240[110][124]

*Theoretical estimate

Thresholds on 2D correlated systems[]

Assuming power-law correlations ${\displaystyle C(r)\sim |r|^{-\alpha }}$

Thresholds on slabs[]

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	${\displaystyle {\overline {z}}}$	Site percolation threshold	Bond percolation threshold
simple cubic (open b.c.)	2	5	5	0.47424,[126] 0.4756[127]
bcc (open b.c.)	2			0.4155[127]
hcp (open b.c.)	2			0.2828[127]
diamond (open b.c.)	2			0.5451[127]
simple cubic (open b.c.)	3			0.4264[127]
bcc (open b.c.)	3			0.3531[127]
bcc (periodic b.c.)	3				0.21113018(38)[128]
hcp (open b.c.)	3			0.2548[127]
diamond (open b.c.)	3			0.5044[127]
simple cubic (open b.c.)	4			0.3997,[126] 0.3998[127]
bcc (open b.c.)	4			0.3232[127]
bcc (periodic b.c.)	4				0.20235168(59)[128]
hcp (open b.c.)	4			0.2405[127]
diamond (open b.c.)	4			0.4842[127]
simple cubic (periodic b.c.)	5	6	6		0.278102(5)[128]
simple cubic (open b.c.)	6			0.3708[127]
simple cubic (periodic b.c.)	6	6	6		0.272380(2)[128]
bcc (open b.c.)	6			0.2948[127]
hcp (open b.c.)	6			0.2261[127]
diamond (open b.c.)	6			0.4642[127]
simple cubic (periodic b.c.)	7	6	6	0.3459514(12)[128]	0.268459(1)[128]
simple cubic (open b.c.)	8			0.3557,[126] 0.3565[127]
simple cubic (periodic b.c.)	8	6	6		0.265615(5)[128]
bcc (open b.c.)	8			0.2811[127]
hcp (open b.c.)	8			0.2190[127]
diamond (open b.c.)	8			0.4549[127]
simple cubic (open b.c.)	12			0.3411[127]
bcc (open b.c.)	12			0.2688[127]
hcp (open b.c.)	12			0.2117[127]
diamond (open b.c.)	12			0.4456[127]
simple cubic (open b.c.)	16			0.3219,[126] 0.3339[127]
bcc (open b.c.)	16			0.2622[127]
hcp (open b.c.)	16			0.2086[127]
diamond (open b.c.)	16			0.4415[127]
simple cubic (open b.c.)	32			0.3219,[126]
simple cubic (open b.c.)	64			0.3165,[126]
simple cubic (open b.c.)	128			0.31398,[126]

Thresholds on 3D lattices[]

Lattice	z	${\displaystyle {\overline {z}}}$	filling factor*	filling fraction*	Site percolation threshold	Bond percolation threshold
(10,3)-a oxide (or site-bond)[129]	23 32	2.4			0.748713(22)[129]	= (pc,bond(10,3) – a)1/2 = 0.742334(25)[130]
(10,3)-b oxide (or site-bond)[129]	23 32	2.4	0.233[131]	0.174	0.745317(25)[129]	= (pc,bond(10,3) – b)1/2 = 0.739388(22)[130]
silicon dioxide (diamond site-bond)[129]	4,22	2 ⅔			0.638683(35)[129]
Modified (10,3)-b[132]	32,2	2 ⅔				0.627[132]
(8,3)-a[130]	3	3			0.577962(33)[130]	0.555700(22)[130]
(10,3)-a[130] gyroid[133]	3	3			0.571404(40)[130]	0.551060(37)[130]
(10,3)-b[130]	3	3			0.565442(40)[130]	0.546694(33)[130]
cubic oxide (cubic site-bond)[129]	6,23	3.5			0.524652(50)[129]
bcc dual		4			0.4560(6)[134]	0.4031(6)[134]
ice Ih	4	4	π √3 / 16 = 0.340087	0.147	0.433(11)[135]	0.388(10)[136]
diamond (Ice Ic)	4	4	π √3 / 16 = 0.340087	0.1462332	0.4299(8),[137] 0.4299870(4),[138] 0.426(+0.08,–0.02),[139] 0.4297(4) [140] 0.4301(4),[141] 0.428(4),[142] 0.425(15),[143] 0.425,[36][41] 0.436(12),[135]	0.3895892(5),[138] 0.3893(2),[141] 0.3893(3),[140] 0.388(5),[143] 0.3886(5),[137] 0.388(5)[142] 0.390(11),[136]
diamond dual		6 2/3			0.3904(5)[134]	0.2350(5)[134]
3D kagome (covering graph of the diamond lattice)	6		π √2 / 12 = 0.37024	0.1442	0.3895(2)[144] =pc(site) for diamond dual and pc(bond) for diamond lattice[134]	0.2709(6)[134]
Bow-tie stack dual		5⅓			0.3480(4)[33]	0.2853(4)[33]
honeycomb stack	5	5			0.3701(2)[33]	0.3093(2)[33]
octagonal stack dual	5	5			0.3840(4)[33]	0.3168(4)[33]
pentagonal stack		5⅓			0.3394(4)[33]	0.2793(4)[33]
kagome stack	6	6	0.453450	0.1517	0.3346(4)[33]	0.2563(2)[33]
fcc dual	42,8	5 1/3			0.3341(5)[134]	0.2703(3)[134]
simple cubic	6	6	π / 6 = 0.5235988	0.1631574	0.307(10),[143] 0.307,[36] 0.3115(5),[145] 0.3116077(2),[146] 0.311604(6),[147] 0.311605(5),[148] 0.311600(5),[149] 0.3116077(4),[150] 0.3116081(13),[151] 0.3116080(4),[152] 0.3116060(48),[153] 0.3116004(35),[154] 0.31160768(15)[138]	0.247(5),[143] 0.2479(4),[137] 0.2488(2),[155] 0.24881182(10),[146] 0.2488125(25),[156] 0.2488126(5),[157]
hcp dual	44,82	5 1/3			0.3101(5)[134]	0.2573(3)[134]
dice stack	5,8	6	π √3 / 9 = 0.604600	0.1813	0.2998(4)[33]	0.2378(4)[33]
bow-tie stack	7	7			0.2822(6)[33]	0.2092(4)[33]
Stacked triangular / simple hexagonal	8	8			0.26240(5),[158] 0.2625(2),[159] 0.2623(2)[33]	0.18602(2),[158] 0.1859(2)[33]
octagonal (union-jack) stack	6,10	8			0.2524(6)[33]	0.1752(2)[33]
bcc	8	8			0.243(10),[143] 0.243,[36] 0.2459615(10),[152] 0.2460(3),[160] 0.2464(7),[137] 0.2458(2)[141]	0.178(5),[143] 0.1795(3),[137] 0.18025(15),[155] 0.1802875(10),[157]
simple cubic with 3NN (same as bcc)	8	8			0.2455(1),[161] 0.2457(7)[162]
fcc, D3	12	12	π / (3 √2) = 0.740480	0.147530	0.195,[36] 0.198(3),[163] 0.1998(6),[137] 0.1992365(10),[152] 0.19923517(20),[138] 0.1994(2),[141] 0.199236(4)[164]	0.1198(3),[137] 0.1201635(10)[157] 0.120169(2)[164]
hcp	12	12	π / (3 √2) = 0.740480	0.147545	0.195(5),[143] 0.1992555(10)[165]	0.1201640(10)[165] 0.119(2)[143]
La2−x Srx Cu O4	12	12			0.19927(2)[166]
simple cubic with 2NN (same as fcc)	12	12			0.1991(1)[161]
simple cubic with NN+4NN	12	12			0.15040(12)[167]	0.1068263(7)[168]
simple cubic with 3NN+4NN	14	14			0.20490(12)[167]	0.1012133(7)[168]
bcc NN+2NN (= sc(3,4) sc-3NN+4NN)	14	14			0.175,[36] 0.1686(20)[169]	0.0991(5)[169]
Nanotube fibers on FCC	14	14			0.1533(13)[170]
simple cubic with NN+3NN	14	14			0.1420(1)[161]	0.0920213(7)[168]
simple cubic with 2NN+4NN	18	18			0.15950(12)[167]	0.0751589(9)[168]
simple cubic with NN+2NN	18	18			0.137,[41] 0.136[171] 0.1372(1),[161] 0.13735(5)[citation needed]	0.0752326(6) [168]
fcc with NN+2NN (=sc-2NN+4NN)	18	18			0.136[36]
simple cubic with short-length correlation	6+	6+			0.126(1)[172]
simple cubic with NN+3NN+4NN	20	20			0.11920(12)[167]	0.0624379(9)[168]
simple cubic with 2NN+3NN	20	20			0.1036(1)[161]	0.0629283(7)[168]
simple cubic with NN+2NN+4NN	24	24			0.11440(12)[167]	0.0533056(6)[168]
simple cubic with 2NN+3NN+4NN	26	26			0.11330(12)[167]	0.0474609(9)
simple cubic with NN+2NN+3NN	26	26			0.097,[36] 0.0976(1),[161] 0.0976445(10)[citation needed]	0.0497080(10)[168]
bcc with NN+2NN+3NN	26	26			0.095[41]
simple cubic with NN+2NN+3NN+4NN	32	32			0.10000(12)[167]	0.0392312(8)[168]
fcc with NN+2NN+3NN	42	42			0.061,[41] 0.0610(5)[171]
fcc with NN+2NN+3NN+4NN	54	54			0.0500(5)[171]

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 * p_c(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 ^[173]

Dimer percolation in 3D[]

Thresholds for 3D continuum models[]

All overlapping except for jammed spheres and polymer matrix.

System	Φc	ηc
Spheres of radius r	0.289,[176] 0.293,[177] 0.286,[178] 0.295.[85] 0.2895(5),[179] 0.28955(7),[180] 0.2896(7),[181] 0.289573(2),[182] 0.2896,[183] 0.2854,[184] 0.290,[185] 0.290[186]	0.3418(7),[179] 0.341889(3),[182] 0.3360,[184] 0.34189(2) [98] [corrected], 0.341935(8) [187]
Oblate ellipsoids with major radius r and aspect ratio 4/3	0.2831[184]	0.3328[184]
Prolate ellipsoids with minor radius r and aspect ratio 3/2	0.2757,[183] 0.2795,[184] 0.2763[185]	0.3278[184]
Oblate ellipsoids with major radius r and aspect ratio 2	0.2537,[183] 0.2629,[184] 0.254[185]	0.3050[184]
Prolate ellipsoids with minor radius r and aspect ratio 2	0.2537,[183] 0.2618,[184] 0.25(2),[188] 0.2507[185]	0.3035,[184] 0.29(3)[188]
Oblate ellipsoids with major radius r and aspect ratio 3	0.2289[184]	0.2599[184]
Prolate ellipsoids with minor radius r and aspect ratio 3	0.2033,[183] 0.2244,[184] 0.20(2)[188]	0.2541,[184] 0.22(3)[188]
Oblate ellipsoids with major radius r and aspect ratio 4	0.2003[184]	0.2235[184]
Prolate ellipsoids with minor radius r and aspect ratio 4	0.1901,[184] 0.16(2)[188]	0.2108,[184] 0.17(3)[188]
Oblate ellipsoids with major radius r and aspect ratio 5	0.1757[184]	0.1932[184]
Prolate ellipsoids with minor radius r and aspect ratio 5	0.1627,[184] 0.13(2)[188]	0.1776,[184] 0.15(2)[188]
Oblate ellipsoids with major radius r and aspect ratio 10	0.0895,[183] 0.1058[184]	0.1118[184]
Prolate ellipsoids with minor radius r and aspect ratio 10	0.0724,[183] 0.08703,[184] 0.07(2)[188]	0.09105,[184] 0.07(2)[188]
Oblate ellipsoids with major radius r and aspect ratio 100	0.01248[184]	0.01256[184]
Prolate ellipsoids with minor radius r and aspect ratio 100	0.006949[184]	0.006973[184]
Oblate ellipsoids with major radius r and aspect ratio 1000	0.001275[184]	0.001276[184]
Oblate ellipsoids with major radius r and aspect ratio 2000	0.000637[184]	0.000637[184]
Spherocylinders with H/D = 1	0.2439(2)[181]
Spherocylinders with H/D = 4	0.1345(1)[181]
Spherocylinders with H/D = 10	0.06418(20)[181]
Spherocylinders with H/D = 50	0.01440(8)[181]
Spherocylinders with H/D = 100	0.007156(50)[181]
Spherocylinders with H/D = 200	0.003724(90)[181]
Aligned cylinders	0.2819(2)[189]	0.3312(1)[189]
Aligned cubes of side ${\displaystyle \ell =2a}$	0.2773(2)[99] 0.27727(2),[43] 0.27730261(79)[153]	0.3247(3),[98] 0.3248(3),[99] 0.32476(4)[189] 0.324766(1)[153]
Randomly oriented icosahedra		0.3030(5)[190]
Randomly oriented dodecahedra		0.2949(5)[190]
Randomly oriented octahedra		0.2514(6)[190]
Randomly oriented cubes of side ${\displaystyle \ell =2a}$	0.2168(2)[99] 0.2174,[183]	0.2444(3),[99] 0.2443(5)[190]
Randomly oriented tetrahedra		0.1701(7)[190]
Randomly oriented disks of radius r (in 3D)		0.9614(5)[191]
Randomly oriented square plates of side ${\displaystyle {\sqrt {\pi }}r}$		0.8647(6)[191]
Randomly oriented triangular plates of side ${\displaystyle {\sqrt {2\pi }}/3^{1/4}r}$		0.7295(6)[191]
Voids around disks of radius r		22.86(2)[192]
Voids around oblate ellipsoids of major radius r and aspect ratio 10		15.42(1)[192]
Voids around oblate ellipsoids of major radius r and aspect ratio 2		6.478(8)[192]
Voids around hemispheres	0.0455(6)[193]
Voids around aligned tetrahedra	0.0605(6)[194]
Voids around rotated tetrahedra	0.0605(6)[194]
Voids around aligned cubes	0.036(1),[43] 0.0381(3)[194]
Voids around rotated cubes	0.0381(3)[194]
Voids around aligned octahedra	0.0407(3)[194]
Voids around rotated octahedra	0.0398(5)[194]
Voids around aligned dodecahedra	0.0356(3)[194]
Voids around rotated dodecahedra	0.0360(3)[194]
Voids around aligned icosahedra	0.0346(3)[194]
Voids around rotated icosahedra	0.0336(7)[194]
Voids around spheres	0.034(7),[195] 0.032(4),[196] 0.030(2),[104] 0.0301(3),[197] 0.0294,[198] 0.0300(3),[199] 0.0317(4),[200] 0.0308(5)[193] 0.0301(1)[194]	3.506(8),[199] 3.515(6),[192] 3.510(2)[88]
Jammed spheres (average z = 6)	0.183(3),[201] 0.1990,[202] see also contact network of jammed spheres	0.59(1)[201]

${\displaystyle \eta _{c}=(4/3)\pi r^{3}N/L^{3}}$ is the total volume (for spheres), where N is the number of objects and L is the system size.

${\displaystyle \phi _{c}=1-e^{-\eta _{c}}}$ is the critical volume fraction.

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

For void ("Swiss-Cheese" model), ${\displaystyle \phi _{c}=e^{-\eta _{c}}}$ is the critical void fraction.

For more results on void percolation around ellipsoids and elliptical plates, see.^[192]

For more ellipsoid percolation values see.^[184]

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.^[181]

For superballs, m is the deformation parameter, the percolation values are given in.,^[203][204] In addition, the thresholds of concave-shaped superballs are also determined in ^[106]

For cuboid-like particles (superellipsoids), m is the deformation parameter, more percolation values are given in.^[183]

Thresholds on 3D random and quasi-lattices[]

Lattice	z	${\displaystyle {\overline {z}}}$	Site percolation threshold	Bond percolation threshold
Contact network of packed spheres		6	0.310(5),[201] 0.287(50),[205] 0.3116(3),[202]
Random-plane tessellation, dual		6	0.290(7)[206]
Icosahedral Penrose		6	0.285[207]	0.225[207]
Penrose w/2 diagonals		6.764	0.271[207]	0.207[207]
Penrose w/8 diagonals		12.764	0.188[207]	0.111[207]
Voronoi network		15.54	0.1453(20)[169]	0.0822(50)[169]

Thresholds for other 3D models[]

Lattice	z	${\displaystyle {\overline {z}}}$	Site percolation threshold	Bond percolation threshold
Drilling percolation, simple cubic lattice*	6	6	6345(3),[208] 0.6339(5),[209] 0.633965(15)[210]
Random tube model, simple cubic lattice†				0.231456(6)[211]

${\displaystyle ^{*}}$ In drilling percolation, the site threshold represents the fraction of columns that have not been removed.

^† In tube percolation, the bond threshold represents the value of the parameter ${\displaystyle \mu }$ such that the probability of putting a bond between neighboring vertical tube segments is ${\displaystyle 1-e^{-\mu h_{i}}}$, where ${\displaystyle h_{i}}$ is the overlap height of two adjacent tube segments.^[211]

Thresholds in different dimensional spaces[]

Continuum models in higher dimensions[]

${\displaystyle \eta _{c}=(\pi ^{d/2}/\Gamma [d/2+1])r^{d}N/L^{d}.}$

In 4d, ${\displaystyle \eta _{c}=(1/2)\pi ^{2}r^{4}N/L^{4}}$.

In 5d, ${\displaystyle \eta _{c}=(8/15)\pi ^{2}r^{5}N/L^{5}}$.

In 6d, ${\displaystyle \eta _{c}=(1/6)\pi ^{3}r^{6}N/L^{6}}$.

${\displaystyle \phi _{c}=1-e^{-\eta _{c}}}$ is the critical volume fraction.

For void models, ${\displaystyle \phi _{c}=e^{-\eta _{c}}}$ is the critical void fraction, and ${\displaystyle \eta _{c}}$ is the total volume of the overlapping objects

Thresholds on hypercubic lattices[]

For thresholds on high dimensional hypercubic lattices, we have the asymptotic series expansions ^{[213] [222] [223]}

${\displaystyle p_{c}^{\mathrm {site} }(d)=\sigma ^{-1}+{\frac {3}{2}}\sigma ^{-2}+{\frac {15}{4}}\sigma ^{-3}+{\frac {83}{4}}\sigma ^{-4}+{\frac {6577}{48}}\sigma ^{-5}+{\frac {119077}{96}}\sigma ^{-6}+{\mathcal {O}}(\sigma ^{-7})}$

${\displaystyle p_{c}^{\mathrm {bond} }(d)=\sigma ^{-1}+{\frac {5}{2}}\sigma ^{-3}+{\frac {15}{2}}\sigma ^{-4}+57\sigma ^{-5}+{\frac {4855}{12}}\sigma ^{-6}+{\mathcal {O}}(\sigma ^{-7})}$

where ${\displaystyle \sigma =2d-1}$.

Thresholds in other higher-dimensional lattices[]

d	lattice	z	Site thresholds	Bond thresholds
4	diamond	5	0.2978(2)[141]	0.2715(3)[141]
4	kagome	8	0.2715(3)[144]	0.177(1) [141]
4	bcc	16	0.1037(3)[141]	0.074(1),[141] 0.074212(1)[219]
4	fcc, D4	24	0.0842(3),[141] 0.08410(23),[217] 0.0842001(11)[164]	0.049(1),[141] 0.049517(1),[219] 0.0495193(8)[164]
4	cubic NN+2NN	32	0.06190(23)[217]	0.035827(1)[219]
4	cubic 3NN	32	0.04540(23)[217]
4	cubic NN+3NN	40	0.04000(23)[217]
4	cubic 2NN+3NN	58	0.03310(23)[217]
4	cubic NN+2NN+3NN	64	0.03190(23)[217]
5	diamond	6	0.2252(3)[141]	0.2084(4)[144]
5	kagome	10	0.2084(4)[144]	0.130(2)[141]
5	bcc	32	0.0446(4)[141]	0.033(1)[141]
5	fcc, D5	40	0.0431(3),[141] 0.0435913(6)[164]	0.026(2),[141] 0.0271813(2)[164]
6	diamond	7	0.1799(5)[141]	0.1677(7)[144]
6	kagome	12	0.1677(7)[144]
6	fcc, D6	60	0.0252(5),[141] 0.02602674(12)[164]	0.01741556(5)[164]
6	bcc	64	0.0199(5)[141]
6	E6[164]	72	0.02194021(14)[164]	0.01443205(8)[164]
7	fcc, D7	84	0.01716730(5)[164]	0.012217868(13)[164]
7	E7[164]	126	0.01162306(4)[164]	0.00808368(2)[164]
8	fcc, D8	112	0.01215392(4)[164]	0.009081804(6)[164]
8	E8[164]	240	0.00576991(2)[164]	0.004202070(2)[164]
9	fcc, D9	144	0.00905870(2)[164]	0.007028457(3)[164]
9	${\displaystyle \Lambda _{9}}$[164]	272	0.00480839(2)[164]	0.0037006865(11)[164]
10	fcc, D10	180	0.007016353(9)[164]	0.005605579(6)[164]
11	fcc, D11	220	0.005597592(4)[164]	0.004577155(3)[164]
12	fcc, D12	264	0.004571339(4)[164]	0.003808960(2)[164]
13	fcc, D13	312	0.003804565(3)[164]	0.0032197013(14)[164]

Thresholds in one-dimensional long-range percolation[]

Long-range bond percolation model. The lines represent the possible bonds with width decreasing as the connection probability decreases (left panel). An instance of the model together with the clusters generated (right panel).

Critical thresholds ${\displaystyle C_{c}}$ as a function of ${\displaystyle \sigma }$.^[224] The dotted line is the rigorous lower bound.^[225]

In a one-dimensional chain we establish bonds between distinct sites ${\displaystyle i}$ and ${\displaystyle j}$ with probability ${\displaystyle p={\frac {C}{|i-j|^{1+\sigma }}}}$ decaying as a power-law with an exponent ${\displaystyle \sigma >0}$. Percolation occurs^[225][226] at a critical value ${\displaystyle C_{c}<1}$ for ${\displaystyle \sigma <1}$. The numerically determined percolation thresholds are given by:^[224]