Critical behavior of a three-state Potts model on a Voronoi lattice

We use the single-histogram technique to study the critical behavior of the three-state Potts model on a (random) Voronoi-Delaunay lattice with size r anging from 250 to 8000 sites. We consider the effect of an exponential dec ay of the interactions with the distance, J(r) = J(0) exp(-ar), with a > 0, and observe that this system seems to have critical exponents gamma and nu which are different from the respective exponents of the three-state Potts model on a regular square lattice. However, the ratio gamma/nu remains ess entially the same. We find numerical evidences (although not conclusive, du e to the small range of system size) that the specific heat on this random system behaves as a power-law for a = 0 and as a logarithmic divergence for a = 0.5 and a = 1.0.