A simple relationship of bond dissociation energy and average charge separation to impact sensitivity for nitro explosives

Abstract

The bond dissociation energy (BDE) of the weakest bonds in 33 explosives were calculated and analyzed using the B3LYP method with the
6-311++G** basis set. A comparison between BDE and the impact sensitivity H50 showed that cleavage of the weakest bond plays an important role in the initiation of detonation. Using the generalized gradient approximation (GGA) with the Perdew–Burke–Ernzerhof (PBE) method and dispersion-corrected density functional theory (DFT-D), the simulation of compressed TNT (2-methyl-1,3,5-
-trinitrobenzene) and royal demolition explosive (RDX, hexahydro-
-1,3,5-trinitro-1,3,5-triazine) crystals showed that an imbalance of the electrostatic surface potential (ESP) leads to molecular deformation and instability of the explosive under impact pressures. The average charge separation (П) of the molecules was calculated and used to demonstrate the ESP balances. Based on the BDE, П and the experimental H50 values, simple quantitative structure–sensitivity correlations were established for the nitro heterocycles, nitramines, picryl heterocycles and nitro aromatics, respectively. The fitting relationship is simple yet statistically significant with only two variables. The correlation coefficients, R2, are larger than 0.8 with F>F**(0.05) (95 % confidence intervals).