Molecular dynamics simulation of FOX-7 decomposition reaction under high temperature and pressure.

contextThe decompositions of FOX-7 under high temperatures (2750-3750 K) and high pressures (0-50 GPa) were investigated using the ReaxFF-lg reactive force field molecular dynamics method, revealing its thermodynamic evolution and product formation mechanisms. The decomposition products are all NO

methodsMolecular dynamics simulations of FOX-7 were performed using Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) with the ReaxFF-lg force field. A 2 × 4 × 2 supercell was constructed based on X-ray diffraction data, optimized geometrically (0.1 fs time step), equilibrated via NVE ensemble (10 ps, heated from 0 to 300 K) and NPT ensemble (15 ps, 300 K), verifying the applicability of ReaxFF-lg. To study high-temperature and high-pressure effects on FOX-7 thermal decomposition, two approaches were used. First, under NVE ensemble, the system was heated to target temperatures (2750-3750 K.) over 150 ps, then maintained for 150 ps (0.1 fs step, periodic boundaries). Second, initial pressures (0-50 GPa) were applied at 300 K via NPT ensemble for 20 ps, followed by heating to 3500 K over 50 ps under NVE. Atomic trajectories, species, and thermodynamic data were recorded every 10 fs.