Brownian dynamics simulation of gelation and aging in interacting colloidal systems

In this paper we simulate the aggregation of interacting particles using Brownian dynamics. The parameters varied are volume fraction and interaction potential well depth. At volume fractions above 0.07 percolated structures are observed; these are formed differently from cluster-cluster aggregation. Fractal analysis of the structures shows nonuniversal fractal scaling for all systems, with lower bound r(0) and fractal dimensionality d(f). Both of these properties depend on the simulation parameters and on time. Compactification in time leads to an increasing r(0) and a decreasing d(f), that is, structures with thick strands. This effect is most pronounced at large well depths. Due to compactification in time, percolated states can be transient.