冲击波下固相HMX的初始反应机理

Initial decomposition mechanism of solid-state HMX for steady shock waves

通过Car-Parrinello软件包,利用分子动力学方法及多尺度冲击技术(MSST)研究固相HMX晶体在冲击波加载下的分解过程。结果显示,冲击下固相HMX的初始分解路径与冲击波速度有关,在8km/s的低冲击下,分解反应源于N-NO2键的断裂。然而,值得注意的是,当冲击波速度提升到11km/s时,本文中的模拟结果却是C-H反而先于N-NO2断裂,同时伴随大量H离子转移。模拟结果反映出固相HMX在冲击作用下初始起爆反应过程的新机理,为在极端高温高压条件下含能材料的理论及实验研究提供宝贵的参考数据,同时对研制预测和开发更高性能的炸药也具有重要意义。

We performed self-consistent charge density-functional tight-binding(SCC-DFTB)molecular dynamics simulations in conjunction with the multiscale shock technique(MSST)to study the initial chemical processes of solid-state structure octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine(HMX)under shock wave loading.The results show that the initial decomposition of shocked HMX is triggered by the N-NO2bond breaking at the low shock velocity of 8km/s.As the shock velocity increases to 11km/s,the homolytic cleavage of the N-NO2 bond is suppressed under high pressure, the C-H bond dissociation is the primary pathway for HMX decomposition in its early stages.At the same time,five-membered ring formation accompaning with hydrogen transfer from the CH2group to the-NO2 group is also a primary pathway.Our simulations suggest that the initial chemical processes of shocked HMX are dependent on the pressure.The new mechanism provides fundamental insight into the initial mechanism at the atomistic level,which is of important implication for understanding and development of energetic materials.