Geometrical properties of aggregates with tunable fractal dimension

We have computed geometrical characteristics of large clusters (up to 32 768 particles) obtained by a hierarchical cluster-cluster aggregation computer model in three dimensions, the off-lattice variable-D model. Using a 'box-counting' method, we have calculated the fractal dimensions of the surface D-s and the perimeter D-p of their two-dimensional projections as a function of their fractal dimension D. By diagonalizing the radius of gyration tensor, we have obtained numerical estimates for the intrinsic anisotropy coefficients (ratios of the eigenvalues) and we have proposed analytical expressions to describe their behaviour as a function of the fractal dimension.