Molecular evolution mechanisms of FOX-7 under high-pressure shock on different crystal faces

To illustrate atomic-level insights into the physicochemical behavior of 1,1-diamino-2,2-dinitroethylene (FOX-7) under shock stimulation, this study applied pressure of 1 GPa-90 GPa on different crystalline faces through reactive molecular dynamics simulations and provided detailed information about the decomposition of FOX-7 at high pressure. The results show that the (010) face was much more compressible than the (100) face. Shocking the (010) and (100) faces yielded directional bulk moduli of 13.5 GPa and 29.1 GPa, respectively, and material sound velocities of 2.5 km & BULL; s-1 and 4.3 km & BULL; s-1, respectively. Under pressure below 60 GPa, the initial shock decomposition pathway of the (010) face was the intramolecular hydrogen (H) transfer, while that of the (100) face included dimerization and intermolecular H transfer. However, the difference in the reaction pathway faded away under pressure of around 80 GPa. Under all conditions, the main final small molecule fragments included N2 and H2O. Unlike thermal decomposition, in which FOX-7 yields NO2 via direct rupture, the high-pressure shock caused FOX-7 to produce carbon clusters with a few gaseous products.