Nanoscale Molecular Dynamics Simulaton of Shock Compression of Silicon

We report results of molecular dynamics simulation of shock wave propagation in silicon in [100], [110], and [111] directions obtained using a classical environment-dependent interatomic potential (EDIP). Several regimes of materials response are classified as a function of shock wave intensity using the calculated shock Hugoniot. Shock wave structure in [100] and [111] directions exhibit usual evolution as a function of piston velocity. At piston velocities 1.25< vp < 2.75 km/s the shock wave consists of a fast elastic precursor followed by a slower plastic front. At larger piston velocities the single overdriven plastic wave propagates through the crystal causing amorphization of Si. However, the [110] shock wave exhibits an anomalous materials response at intermediate piston velocities around vp ~= 1.75 km/s which is characterized by the absence of plastic deformations.