ANIMATED MOLECULAR-DYNAMICS SIMULATIONS OF ENERGETIC MIXED CLUSTER IMPACTS

Molecular dynamics and computer animation techniques have been used to investigate atom ejection and damage caused by the impact of energetic, uniformly mixed Al32Au31 clusters on 12-layer, 3750-atom Au(100) targets at total cluster energies of 5, 10, 50, 100, and 200 keV. At all incident energies we find that a significant fraction of the aluminum is ejected from the cluster on impact. At the two lowest bombarding energies damage to the target is limited generally to the primary impact zone, and crystallinity is retained throughout most of the the target. At the higher bombarding energies significant damage occurs throughout the central region of the target, and crystallinity is lost throughout the entire target. In contrast to collision cascades initiated by single ions, those initiated by energetic clusters are observed to be highly nonlinear (essentially all the atoms in the cascade region are in motion) and to propagate through the target with relatively uniform wavefronts.