The layered crystal structure of the explosive ICM-102 (2,4,6-triamino-5-nitropyrimidine-1,3-dioxide) exhibits an extremely low sensitivity, and furthermore, the layering is observed to induce typical anisotropy. To elucidate the anisotropic initial reaction mechanism, ReaxFF-lg reactive molecular dynamic simulations were performed to investigate the shock-induced reaction of ICM-102 by the piston impact on the supercell directly along different directions at various velocities. A novel method is proposed, which eliminates the boundary reflection at the supercell edge and studies prolonged simulations of the explosive reaction within a small supercell. When subjected to shock loadings along the x and y axes, which are parallel to the multilayers, the layered structure is at first observed to bend prior to undergoing a dimerization reaction via intermolecular O–O or O–H bond formation between the ICM-102 molecules in the same layer. When subjected to shock loading along the z axis, which is perpendicular to the multilayers, the interlayer space is first compressed leading to a dimerization reaction via N–O or C–N bond formation between the ICM-102 molecules from different layers. The energy for dimerization of the molecules in the same layer is lower, and hence, dimerization is observed to be easier. The reaction of ICM-102 is the most intense when the shock loading along the x axis is of the same strength as the shock loading along the other directions. A critical pressure is observed when the reaction rate of ICM-102 changes from slow to fast regardless of the shock loading direction. The critical pressure correlates well with shock sensitivity. The most sensitive orientation of ICM-102 is x axis > y axis > z axis.

中文翻译：

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冲击载荷下层状晶体结构炸药ICM-102的各向异性初始反应机理及敏感性表征

爆炸性ICM-102的层状晶体结构（2,4,6-三氨基-5-硝基嘧啶-1,3-二氧化物）显示出极低的灵敏度，此外，观察到该层状引发典型的各向异性。为了阐明各向异性的初始反应机理，进行了ReaxFF-lg反应性分子动力学模拟，以研究活塞在不同速度下沿不同方向直接作用于超级电池时，ICM-102的冲击诱导反应。提出了一种新颖的方法，该方法消除了超级电池边缘的边界反射，并研究了小型超级电池内爆炸反应的长时间模拟。当受到沿x和y的冲击载荷时在平行于多层的两个轴上，首先观察到层状结构发生弯曲，然后通过同一层中ICM-102分子之间的分子间O-O或O-H键形成二聚化反应。当沿垂直于多层的z轴承受冲击载荷时，层间空间首先被压缩，从而通过不同层的ICM-102分子之间形成的N-O或C-N键形成二聚反应。同一层中分子二聚化的能量较低，因此观察到二聚化更容易。当沿x的冲击载荷作用时，ICM-102的反应最强烈轴的强度与沿其他方向的冲击载荷相同。当ICM-102的反应速率从慢到快变化时，无论冲击载荷的方向如何，都会观察到临界压力。临界压力与冲击敏感性密切相关。ICM-102最敏感的方向是x轴> y轴> z轴。