Physical review. B, Condensed matter
New real-space renormalization techniques and their application to models of various spin and space dimensionalities
Wolfgang Kinzel
Abstract
The mean-field approximation is used for the evaluation of the Niemeijer---Van Leeuwen real-space renormalization. Although this new method is very simple, it gives reasonable results for the critical properties of two-, three-, and four-dimensional Ising models, for the transition temperature ${T}_{c}$ of an Ising model with clusters and for the two-dimensional Ising antiferromagnet in an external magnetic field. Using this new mean-field renormalization in connection with the real-space renormalization of the kinetic Ising model, which recently has been suggested by the author, we obtain the long-time relaxation of the magnetization for all temperatures above ${T}_{c}$. In the last application the critical properties of $n$-dimensional spins in two and three space dimensions are calculated for arbitrary $n$. Here the mean-field approximation and Monte Carlo methods are used to evaluate the renormalization step.