Large-scale molecular dynamics simulations of hyperthermal cluster impact

Using multimillion-atom classical molecular dynamics simulations, we have studied the impact dynamics of solid and liquid spherical copper clusters (10–30 nm radius) with a solid surface, at velocities ranging from 100 m/s to 2 km/s. The resulting shock, jetting, and fragmentation processes are analyzed, demonstrating three distinct mechanisms for fragmentation. At early times, shock-induced ejection and hydrodynamic jetting produce fragments in the normal and tangential directions, respectively, while sublimation (evaporation) from the shock-heated solid (liquid) surface produces an isotropic fragment flux at both early and late times.