  We numerically simulate the dynamics of aggregation of interacting atomic
clusters deposited on a surface. We show that the shape of the structures
resulting from their aggregation-limited random walk is affected by the
presence of a binary interparticle Laplacian potential due to, for instance,
the surface stress field. We characterize the morphologies we obtain by their
Hausdorff fractal dimension as well as the so-called external fractal
dimension, which appears more sensitive to the potential. We demonstrate the
relevance of our model by comparing it to previously published experimental
results for antymony and silver clusters deposited onto graphite surface.
