Molecular dynamic insight into octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and the nano-HMX decomposition mechanism

Abstract

Herein, we demonstrate the use of large-scale reactive molecular dynamics simulations to identify the influence of nanostructures, size effects, and temperature for the decomposition processes of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX). The bulk-phase and six types of HMX nanoparticle (30–70 Å) systems were investigated at two high temperatures (2000 K and 3000 K). The evolution of the potential energy (PE) and total number of molecules (TM) of HMX crystals and their six nanoparticle systems were analyzed and addressed, and it was revealed that the nanostructure has a great accelerative effect on the thermal decomposition of HMX. The temperature distribution, initial decomposition process, and main intermediate and gas products were traced, and showed that the initial decomposition of HMX nanoparticles is triggered by the dissociation of the N–NO₂ bond. With the increase in temperature, the total amount of gas molecules in HMX nanoparticles rapidly increases, which shows that the high temperature can accelerate the decomposition rate for HMX nanoparticles.