Computer simulation of the nonequilibrium critical behavior of disordered two-dimensional Ising systems
We report the results of a computer simulation of the critical relaxation of the magnetization in the two-dimensional Ising model with nonmagnetic impurity atoms frozen at the lattice sites. We assume a square lattice of dimension 4002 with spin concentrations p=1.0, 0.95, 0.9, 0.85, 0.8, 0.75, 0.7. The Monte Carlo and dynamic renormalization group methods are used to determine the dynamical critical index z as a function of p: z(p): z(1)=2.24±0.07, z(0.95)=2.24±0.06, z(0.85)=2.38±0.05, z(0.8)=2.51±0.06, z(0.75)=2.66±0.07, z(0.7)=2.88±0.06. It is shown that z(p) obeys a singular scaling law of the form z=A' | ln ( p-p c) |+ B' with A'=0.56±0.07, B'=1.62±0.07.