Analysis of Path-Dependent, Non-Statistical Mechanochemistry in TATB Hotspots via Unsupervised Learning

Shock loading of plasticly bonded high explosives leads to energy localization into hotspots, which are known to govern the initiation of detonation. Hotspots, and their criticality, have generally been characterized in terms of only their size and temperature. Yet, our recent results show that more energy is localized in potential energy (PE) than in kinetic energy (KE), and this PE rise is more persistent in time. This PE rise is a result of intra-molecular deformation that are unable to relax. However, modeling the effects of mechanical strain on the reaction rates of materials near detonation conditions is still a grand challenge. We use unsupervised clustering to group hotspot molecules by temperature and deformation. We find that for similar temperatures, as molecules reach higher levels of deformation, not only do they react faster, but the distribution of their lifetimes shifts from a Poisson distribution to an exponential decay. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Approved for unlimited release LLNL-ABS-815963.