National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, Chinese Academy of Engineering Physics, Mianyang 621900, China.
J Phys Chem B. 2012 Nov 26;116(46):13696-704. doi: 10.1021/jp309120t. Epub 2012 Nov 13.
We have performed quantum-based multiscale simulations to study the initial chemical processes of condensed-phase octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) under shock wave loading. A self-consistent charge density-functional tight-binding (SCC-DFTB) method was employed. The results show that the initial decomposition of shocked HMX is triggered by the N-NO(2) bond breaking under the low velocity impact (8 km/s). As the shock velocity increases (11 km/s), the homolytic cleavage of the N-NO(2) bond is suppressed under high pressure, the C-H bond dissociation becomes the primary pathway for HMX decomposition in its early stages. It is accompanied by a five-membered ring formation and hydrogen transfer from the CH(2) group to the -NO(2) group. Our simulations suggest that the initial chemical processes of shocked HMX are dependent on the impact velocity, which gain new insights into the initial decomposition mechanism of HMX upon shock loading at the atomistic level, and have important implications for understanding and development of energetic materials.
我们进行了基于量子的多尺度模拟，以研究凝聚相八氢-1,3,5,7-四硝基-1,3,5,7-四唑（HMX）在冲击波加载下的初始化学过程。采用了自洽电荷密度泛函紧束缚（SCC-DFTB）方法。结果表明，在低速冲击（8 km/s）下，N-NO2 键的断裂引发了冲击 HMX 的初始分解。随着冲击速度的增加（11 km/s），高压下 N-NO2 键的均裂被抑制，C-H 键的离解成为 HMX 早期分解的主要途径。同时伴随着五元环的形成以及氢从 CH2 基团向-NO2 基团的转移。我们的模拟表明，冲击 HMX 的初始化学过程取决于冲击速度，这为在原子水平上理解冲击加载下 HMX 的初始分解机制提供了新的见解，并对理解和发展含能材料具有重要意义。
