= Mean-field theory of the Ising model
{title2=$m=\tanh[\beta_T(h+qJm)]$}
= Ising mean-field theory
{c}
{synonym}
The <mean-field approximation> neglects products of <Ising spin> deviations, replacing each <Ising spin>'s neighbours by the common <spin magnetization>. With <coordination number of a lattice> $q$, the effective field is $h+qJm$. The <self-consistency equation> equates the assumed mean <Ising spin> with its independent-spin expectation in that effective field. It predicts $k_BT_c=qJ$ and the usual quartic <mean-field critical exponents>, while neglecting spatially correlated fluctuations.
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