Direct numerical observation of anomalous diffusion in random media

We present computer simulations of anomalous diffusion, [r(2)(t)] similar to at(1-8), in two dimensions. The Monte Carlo calculations are in excellent agreement with previous renormalization group calculations. Interestingly, use of a high-quality pseudorandom number generator is necessary to observe the anomalous diffusion. A linear-feedback, shift-register method leads to incorrect, superdiffusive motion of the random walkers.