Cluster variation method and disorder varieties of two-dimensional Ising-like models
Alessandro Pelizzola
I show that the cluster variation method, long used as a powerful hierarchy of approximations for discrete (Ising-like) two-dimensional lattice models, yields exact results on the disorder varieties which appear when competitive interactions are put into these models. I consider, as an example, the plaquette approximation of the cluster variation method for the square lattice Ising model with nearest-neighbor, next-nearest-neighbor, and plaquette interactions, and, after rederiving known results, report simple closed-form expressions for the pair and plaquette correlation functions.
arXiv:cond-mat/9909361•Physical review. B, Condensed matter•May 1, 2000•9 citations