The ferromagnetic Ising model on a Voronoi-Delaunay lattice

We investigate the two-dimensional ferromagnetic Ising model in the Voronoi -Delaunay tesselation. In this study, we assume that the coupling factor J varies with the distance r between the first neighbors as J(r) proportional to e(-alpha r), with alpha greater than or equal to 0. The disordered syst em is simulated applying the single-cluster Monte Carlo update algorithm an d the reweighting technique. We calculate the critical point exponents gamm a/nu, beta/nu and nu for this model and find that this random system belong s to the same universality class as the pure two-dimensional ferromagnetic Ising model. (C) 2000 Elsevier Science B.V. All rights reserved.