Computer simulations of dense-branching patterns

We present a novel Monte Carlo simulation of electrochemical deposition that shows a smooth transition between diffusion limited aggregation and dense-branching morphology. The essential element of the simulation is to divide the growth field into two areas, a ``space charge'' region surrounding the aggregate in which particle motion is biased to branch tips, and a second region surrounding the first in which particle motion follows unbiased random walks. The interface between these areas is stable to perturbations of wavelength smaller than the size of the space charge region.