Nonuniversality in short-time critical dynamics

We study the behaviour of dynamical critical exponents of the two-dimensional Ising model with a line of defects. Simulations done at an early time (first 100 Monte Carlo steps) reveal that the critical exponent of Janssen et al ( Z. Phys. B 73 539) depends on the strength of the exchange coupling constant of the altered line. On the other hand, our simulations permit us to conclude that the dynamical critical exponent z is not sensitive to changes in . In addition, we investigate the possible invariance of the anomalous dimension of the magnetization at the beginning of the process.