Stochastic hierarchical model for cluster-cluster aggregation.

A stochastic hierarchical model of cluster-cluster aggregation, which is obtained by introducing a sticking probability into the recently proposed hierarchical model by Sornsen and Oh [Phys. Rev. E 58, 7545 (1998)], is presented. The fractal dimension and aspect ratio calculated using the model give good agreement with those obtained in standard simulations of cluster-cluster aggregates. An interesting result is that the fractal dimension shows a peak as a function of the sticking probability.