Stochastic hierarchical model for cluster-cluster aggregation

A stochastic hierarchical model of cluster-cluster aggregation, which is ob tained by introducing a sticking probability into the recently proposed hie rarchical model by Sornsen and Oh [Phys. Rev. E 58, 7545 (1998)], is presen ted. The fractal dimension and aspect ratio calculated using the model give good agreement with those obtained in standard simulations of cluster-clus ter aggregates. An interesting result is that the fractal dimension shows a peak as a function of the sticking probability. [S1063-651X(99)17310-0].