Decomposition of 5-(Dinitromethylene)-4,5-dihydro-1H-1,2,4-triazole at elevated temperatures coupled with high pressures: A molecular dynamics study.

The thermal decomposition mechanisms of 5-(dinitromethylene)-4,5-dihydro-1H-1,2,4-triazole (DNMDHT), a FOX-7 derivative, were systematically investigated under extreme conditions via ReaxFF-lg reactive molecular dynamics simulations. Two distinct regimes were examined: (1) high-temperature conditions (2500-3500 K) and (2) combined high-temperature-high-pressure conditions (3000 K, 0-50 GPa). There are two possible decomposition pathways for DNMDHT-FOX, one of which is that the DNMDHT-FOX molecule will first undergo condensation under high-temperature, and polymerized to form a polymer under high-pressure, then the decomposition pathway initiates with sequential C-N bond cleavages, first eliminating nitro groups followed by ring-opening, succeeded by C=C and C=N bond ruptures. Primary decomposition products include H₂O, CO₂, N₂, H₂, and NH₃ as stable products, with NO₂, NO, and CO identified as key intermediates. Notably, pressure-dependent studies revealed NH₃ yields increase monotonically with pressure (0-50 GPa), while all other product yields demonstrate inverse pressure dependence. These findings establish that temperature accelerates decomposition kinetics whereas pressure exerts an inhibitory effect, except for NH₃ formation. This work provides fundamental insights into the decomposition chemistry of energetic FOX-7 derivatives under extreme conditions, offering valuable guidance for the design and safety evaluation of novel high-energy materials.