Many-Body Mechanochemistry Simulations: Exploring the initial events inside a hotspot

When molecular materials experience high velocity impacts, the resulting shockwave can induce a variety of complex intra-molecular deformations, leading to mechanochemistry. Mechanochemistry can enable novel reaction pathways, lower the thermal energy cost of reactions, and is relevant to thermochemical phenomena such as detonation, with mounting indication that these effects are highly relevant to the initiation of “hotspots” in high explosives. However, these effects are difficult to assess under non-equilibrium and shock loading simulations, and the state-of-the-art simulation techniques for mechanochemistry typically apply linear forces to individual molecules. Therefore, we develop a novel technique of an external biasing potential to apply ‘many-bodied steered molecular dynamics’ in which we mimic intra-molecular deformations of a shock induced hotspot in TATB. Independent simulations of two different deformation types show different levels of acceleration of reaction kinetics for the applied work and results in different alterations to first-step reaction pathways. We believe these results help to solve the puzzling difference between thermal and shock-loaded kinetics in HEs and provide a more general methodology for assessing mechanochemical affects in bulk, covalent solids.