VARIATIONAL MIGDAL-KADANOFF APPROACH TO MOLECULAR ORDERING ON A LATTICE

A variational extension of the Migdal-Kadanoff real space renormalizat ion group method is applied to a recently proposed d-dimensional latti ce model describing some aspects of molecular orientation in solids. A s expected the method yields the exact fixed point for d = 2, given th e formal equivalence to the two-dimensional Ising model. For d = 3 suc h equivalence breaks down and an approximate estimate of the fixed poi nt is explicitly recovered and compared to the mean-field prediction. The possible existence of an intermediate symmetric phase is discussed .