Numerical determination of the phase diagram for thecphi4model in two dimensions

By using a heat-bath Monte Carlo method, combined with extrapolation techniques developed by Ferrenberg and Swendsen [Phys. Rev. Lett. 61, 2635 (1988)], we have determined the line of critical points in the parameter space for the ${\mathit{cphi}}^4$ model on a square lattice. The critical values of the parameters allow us to plot the complete phase diagram of the model. We compare the efficiency of the method to previous results based on numerical solutions of a Langevin equation. In the phase diagram we also show the locations of some of the points where numerical studies of spinodal decomposition have been carried out by several authors.