三类炸药晶体冲击引发分解机理的从头算分子动力学研究

Initial Decomposition Mechanisms of Three Explosive Crystals under Shock Loading by Ab Initio Molecular Dynamics

运用从头算分子动力学和多尺度冲击相结合的方法,对三类典型炸药晶体奥克托今(HMX)、1,3,5-三氨基2,4,6-三硝基苯(TATB)和太安(PETN)实施冲击加载下的模拟研究。结果表明,HMX中的N—O键、TATB中的N—O键以及PETN中的C—O键优先断裂。随着时间推移,他们体系中电子离域性增加;价带和导带间的带隙逐渐减小;接着开始出现金属态并不断变多。在冲击加载下,TATB、HMX和PETN晶体引发断裂化学键所需时间依次减小的顺序,恰与它们冲击波感度依次增大的实验顺序相一致。这表明,它们的结构和引发分解机理与冲击波感度之间有规律性联系。

Ab initio molecular dynamics in conjunction with multiscale shock technique was used to study the initial decomposition of HMX, TATB, and PETN crystals under shock wave loading. Results indicate that the decompositions of HMX, TATB, and PETN under shock loading are triggered by the N--O bond, N--O bond and C--O bond breaking, respectively. As the simulation contin- ues, the electronic delocalization in their systems increases and the band gap between conduction and valence bands decreases grad- ually. Then ,metallic states in the systems begin to appear and increase. Under shock loading, the decreasing order of the time for the trigger bond cleavage for TATB, HMX and PETN is in agreement with the increasing sequence of their experimental shock sensitivity. This suggests that there is a relationship between structure or initiation decomposition mechanisms and sensitivity to shock wave.