Decomposition of HMX at Extreme Conditions: A Molecular Dynamics Simulation

We present the results of a quantum molecular dynamics simulation of the chemistry of HMX, a high performance explosive, at a density of 1.9 g/cm3 and temperature of 3500 K, conditions roughly similar to the Chapman−Jouget detonation state. The molecular forces are determined using the self-consistent-charge density-functional-based tight-binding method. Following the dynamics for a time scale of up to 55 ps allows the construction of effective rate laws for typical products such as H2O, N2, CO2, and CO. We estimate reaction rates for these products of 0.48, 0.08, 0.05, and 0.11 ps-1, respectively. We also find reasonable agreement for the concentrations of dominant species with those obtained from thermodynamic calculations, despite the vastly different theoretical underpinning of these methodologies.