Correlated molecular-field theory for Ising models

The critical temperature $T_c$ of Ising models is obtained quite accurately by simple improvements over the standard molecular-field theory. The important physical effect we include is that the effective field of neighboring spins is influenced by the spin state of the central spin. When used in combination with a self-consistency condition, this correlated molecular-field theory leads to estimates of $T_c$ more accurate than those obtained from the Bethe-Peierls-Weiss approximation.