Evaluating shock sensitivity and decomposition of energetic materials by ReaxFF molecular dynamics

Amorphous models of locally ordered molecular packing were constructed to replace crystals and predict the shock sensibility and safety of energetic materials (EMs) using reactive molecular dynamics. We analyzed the simulation of shock-induced decomposition of EMs, comparing the effects of two different shock modes: the multiscale shock technique (MSST) and quantum-bath-coupled MSST (QBMSST). The rate of temperature rise and decomposition speed differ between these two modes. The critical initiation pressure in EMs is determined when the number of trigger bonds decreases by 15%. The values of the initial pressure for PETN, RDX, TNT, and TATB using QBMSST are 18.44, 24.51, 32.00, and 40.59 GPa, respectively, which are lower than those obtained using MSST. The shock wave sensitivities of these EMs in descending order are PETN, RDX, TNT, and TATB under these two shock modes, which is consistent with experiments. TATB has the highest bulk modulus obtained under both shock modes, followed by TNT, RDX, and PETN. This work demonstrated that the amorphous models like crystal models in the previous literature can be applicable to predict the sensitivity of EMs and could expected to be applicable in mixed or composite systems, including but not limited to shock sensitivities.