DIMENSIONAL CROSSOVERS AND ANOMALOUS SCALING OF SINGLE AND REACTING RANDOM WALKERS IN BAGUETTELIKE LATTICES - MONTE-CARLO SIMULATIONS OF THE NUMBER OF DISTINCT SITES VISITED AND OF BIMOLECULAR A+A AND A+B REACTIONS

We performed Monte Carlo Simulations on baguettelike lattices of rando m-walk-based bimolecular A+A and A+B reactions, and of the number of d istinct sites visited. The emphasis is on the crossover times, from hi gh (two-or three-) dimensional behavior to one-dimensional behavior, a nd their scaling laws with respect to tube width. We find that these d imensional crossovers deviate significantly from a mean square displac ement law and are specific to both tube dimensionality (2 or 3) and re action type (e.g., A+A or A+B), instead of an expected power of 2, the exponents range between 1 and 4. Thus, the global information propaga tion is either faster or slower than single particle diffusion. The fr actional densities of the A+B reactions at the dimensional crossover a re compared to the fractional densities at the segregation crossover i n nonconfined media. The time evolutions of the A+A reactions approxim ately mimic those of the average number of distinct sites visited. All asymptotic time behaviors exhibit one-dimensional character.