Chemical reactions of a CL-20 crystal under heat and shock determined by ReaxFF reactive molecular dynamics simulations

Abstract

Studying the chemical reactions of hexanitrohexaazaisowurtzitane (CL-20) under heat and shock is helpful to understand its sensitivity and shock initiation mechanism. In this work, several molecular dynamics simulations were performed under three different conditions: high temperature, high temperature and pressure, and shock. The formation and breakage of chemical bonds, changes of bond lengths, and initial reactions were analysed. It was found that the main small-molecule product of CL-20 during initial decomposition under the three different conditions was always NO₂, but the generation pathways were different. At high temperatures, NO₂ was generated by the direct cleavage of N–NO₂ bonds. In contrast, high pressure and shock promoted the transfer of O atoms to N atoms connected to NO₂, leading to the breakage of N–NO₂ bonds. Almost all NO₂ originated from the transfer of O atoms under the shock conditions.