Steady-state elastic plastic shock waves in a low-symmetry molecular crystal

JJ Wilkening and SF Son and A Strachan, PHYSICAL REVIEW B, 112, 035406 (2025).

DOI: 10.1103/qn7p-g57s

Large-scale nonequilibrium molecular dynamics simulations of RDX shocked along 100 reveal a steadystate regime of elastic-plastic shock wave propagation along slip-hindered directions in molecular crystals. For a shock with a particle velocity of 1 km/s, steady state is achieved after approximately 100 ps or 0.5 microns from the impact plane. The transient regime is characterized by a dynamic evolution of plasticity, which transitions from the simultaneous nucleation of a high density of shear bands to the growth of fewer shear bands, each resulting in significant localized shear strain and temperature. This evolution of the plastic wave leads to a significant attenuation of the elastic precursor, with a 20% drop in stress along the shock direction. This significant variation in the structure of the shock wave over distances larger than most atomistic simulations to date highlights the need for continuing efforts toward scalable molecular simulations and the challenges in multiscale modeling of dynamical properties.

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