The role of electric field on decomposition of CL-20/HMX cocrystal: A reactive molecular dynamics study

Electric field can initiate decomposition or detonation of explosives, but underlying mechanism is unclear. Here, we performed ReaxFF molecular dynamics simulation for decomposition of a cocrystal, formed by 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane (HMX), solely induced by electric field. A new analytical method was proposed to obtain detailed decomposition mechanism. Results show that electric fields play important roles in decomposition of CL-20/HMX cocrystal, such as heating the system and causing the explosive to decompose. Strong constant field makes CL-20 molecules in the cocrystal decompose at significantly lower temperature, which greatly increases sensitivity. This is ascribed to the distinct decomposition mechanism that CN bond rupture dominates the initial step of CL-20's decomposition. Contrarily, oscillating field has a stronger heating effect but weaker influence on sensitivity. Moreover, HMX exhibits desensitizing effect in CL-20/HMX cocrystal under electric field. These results enhance our understanding of sensitivity mechanism beyond mechanical stimuli in explosives.