Atomic-level view of inelastic deformation in a shock loaded molecular crystal

We use molecular dynamics to characterize the atomic-level mechanisms of plastic deformation in an organic molecular crystal under dynamical loading, namely, -octahydro-1, 3, 5, 7-tetranitro-1, 3, 5, 7-tetrazocine shocked in the 100 direction. Plasticity for weak shocks is governed by dislocations with Burgers vectors b=1∕2 ⟨101⟩ gliding on 101 planes. As the shock strength is increased, we observe a gradual transition to a regime dominated by nanoscale shear bands that does not exhibit a preferred crystallographic slip and where the material becomes locally amorphous.