Complex structure of diamond shock wave front

Shock waves propagate through solids at supersonic speeds and, if powerful enough, can cause inelastic deformations resulting in shock wave splitting into the leading elastic zone followed by a slower inelastic zone. Although the relaxation of shear stresses resulting from uniaxial compression behind the leading elastic front leads to significant variations in major hydrodynamic variables, such as density, particle velocity, and longitudinal and shear stresses, it was previously believed that these changes were limited to elastic relaxation processes, with no defects created behind the elastic front. However, diamond’s exceptional properties challenge this simplified picture. By running extreme-scale, billion atom molecular dynamics simulations with quantum accuracy, we were able to uncover the complex structure of both the elastic and inelastic fronts in diamond shock compressed along the <110> crystallographic directions. At the atomic scale, diamond displays the development of inelastic bond breaking processes in both elastic and inelastic fronts. Interestingly, in addition to extended defects propagating upstream from the inelastic front, the elastic zone of diamond displays the appearance of multiple extended defects even in perfect, elastically compressed material that is far away from the inelastic front. These extended defects seed elastic sound waves that interfere as they propagate towards the leading elastic front, producing visible corrugations on its originally planar surface.