CRITICAL-BEHAVIOR OF THE 3-DIMENSIONAL CONTACT PROCESS

I determine the critical behavior of a nonequilibrium three-dimensional lattice model exhibiting a phase transition to an absorbing state. I study the model in the vicinity of the critical point, and in the subcritical region, via time-dependent Monte Carlo simulations. The method used in the subcritical region is very efficient. The results for the directly measured critical exponents, v = 1.11 +/- 0.01, eta = 0.114 +/- 0.004, and z = 1.052 +/- 0.003, are consistent with those of directed percolation. Delta = 0.732 +/- 0.004 is obtained from the hyperscaling relation 4-delta + 2-eta = dz. and beta = 0.813 +/- 0.011 from beta = v-delta. These results are the most precise so far for a three-dimensional model with directed percolation critical behavior.