Critical Phenomena#

There exists a critical value \(p_{\mathrm{c}}\) of \(p\) such that

\[\begin{split} \theta(p)\begin{cases} =0, & p<p_{\mathrm{c}}\\ >0, & p>p_{\mathrm{c}} \end{cases} \end{split}\]

\(p_{\mathrm{c}}\) is called the critical probability defined as

\[ p_{\mathrm{c}}=\sup\{p\mid\theta(p)=0\} \]

List of known critical probabilities \(p_{\mathrm{c}}\)#

Lattice structure

critical probability \(p_{\mathrm{c}}\)

Square lattice

\(p_{\mathrm{c}}=1/2\)

Triangular lattice

\(p_{\mathrm{c}}=2\sin(\pi/18)=0.34729\dots\)

Hexagonal lattice

\(p_{\mathrm{c}}=1-2\sin(\pi/18)=0.65270\dots\)

bow-tie lattice

\(p_{\mathrm{c}}=p_{c}(\textrm{bow tie})=0.40451\dots\)

Note

\(p_{c}(\textrm{bow tie})\) is the unique solution of the following polynomial in the interval \((0,1)\):

\[ 1-p-6p^{2}+6p^{3}-p^{5}=0 \]