The structure of two-dimensional Witten-Sander aggregates

A relatively large number (10 2 -10 3 ) of reasonably large (about 10 5 particles or sites) two-dimensional Witten-Sander aggregates are simulated using new algorithms. This enables the reduction of statistical errors by an order of magnitude and provides an opportunity to determine some new quantities describing in more detail the structure of Witten-Sander clusters. A quantitate description of the distortion of large lattice-based Witten-Sander clusters into a diamond-like shape is provided. The orientational correlation in the bond directions for off-lattice Witten-Sander clusters is also measured. This quantity has a power law dependence on distance with an exponent of about -0.37.