He Zheng-Hua, Chen Jun, Ji Guang-Fu, Liu Li-Min, Zhu Wen-Jun, Wu Qiang
†National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, Mianyang 621900, Sichuan, China.
‡Beijing Computational Science Research Center, Beijing 100084, China.
J Phys Chem B. 2015 Aug 20;119(33):10673-81. doi: 10.1021/acs.jpcb.5b05081. Epub 2015 Aug 6.
Despite extensive efforts on studying the decomposition mechanism of HMX under extreme condition, an intrinsic understanding of mechanical and chemical response processes, inducing the initial chemical reaction, is not yet achieved. In this work, the microscopic dynamic response and initial decomposition of β-HMX with (1 0 0) surface and molecular vacancy under shock condition, were explored by means of the self-consistent-charge density-functional tight-binding method (SCC-DFTB) in conjunction with multiscale shock technique (MSST). The evolutions of various bond lengths and charge transfers were analyzed to explore and understand the initial reaction mechanism of HMX. Our results discovered that the C-N bond close to major axes had less compression sensitivity and higher stretch activity. The charge was transferred mainly from the N-NO2 group along the minor axes and H atom to C atom during the early compression process. The first reaction of HMX primarily initiated with the fission of the molecular ring at the site of the C-N bond close to major axes. Further breaking of the molecular ring enhanced intermolecular interactions and promoted the cleavage of C-H and N-NO2 bonds. More significantly, the dynamic response behavior clearly depended on the angle between chemical bond and shock direction.
尽管在研究八硝基立方烷（HMX）在极端条件下的分解机理方面付出了巨大努力，但对于引发初始化学反应的机械和化学反应过程的内在理解尚未实现。在这项工作中，借助自洽电荷密度泛函紧束缚方法（SCC-DFTB）结合多尺度冲击技术（MSST），研究了具有（1 0 0）表面和分子空位的β-HMX在冲击条件下的微观动态响应和初始分解。通过分析各种键长和电荷转移的演变，探索并理解HMX的初始反应机理。我们的结果发现，靠近主轴的C-N键具有较低的压缩敏感性和较高的拉伸活性。在早期压缩过程中，电荷主要从N-NO₂基团沿短轴和H原子转移到C原子。HMX的首次反应主要始于靠近主轴的C-N键处分子环的裂变。分子环的进一步断裂增强了分子间相互作用，并促进了C-H键和N-NO₂键的断裂。更重要的是，动态响应行为明显取决于化学键与冲击方向之间的夹角。
