极端条件下典型含能材料分解机理的量子分子动力学研究

Energetic materials have been studied heavily, due to their usage in military and civilian widely. However, the decomposition mechanism of energetic materials under high pressure, which is important for design, exploitation, storage and utilization, is not clear. In our previous study, we have studied the thermal decomposition mechanism of solid nitromethane which is a typical explosive. In this project, explosive decomposition mechanism of solid explosives under extremely high pressure will be studied deeply. The structure and properties as a main line of the nitromethane, starting from the relationship between energy and mechanical properties, study the sensitivity and explosives reaction mechanism by using quantum molecular dynamics simulations method at atomic and molecular level. Utilize the advantages of quantum method, ensuring the accuracy without increasing the amount of computation, to obtain more information during the whole reaction process. Such as the bond breaking and rearrangement in the reaction process, intermediates and transition, and by which intermediate effective chain reaction is caused, determine the microscopic decomposition mechanism of solid nitromethane, this project will be important for not only theoretical studies of explosive reaction, but also the explosive performance calibration, design and development of new explosives, safety and effectiveness of assessment have an important guiding value.

含能材料在军事和民用上具有广泛的应用，一直是世界各国研究的热点问题。然而，极端条件下含能材料的分解机理至今仍不清楚，而此方面的工作对含能材料的设计、开发、存储、利用等都具有非常重要的现实意义。本项目拟在我们前期关于典型含能材料固相硝基甲烷热分解机理研究的基础上，继续深入研究固体炸药（如：硝基甲烷）在极端高压下的爆炸分解行为。以含能材料的结构与性能为主线，从能量与力学性能的关系出发，用量子分子动力学方法从原子分子层面上对固体炸药的分解机理进行研究，研究内容包括：初始分解引发机制、反应路径、反应过程中化学键的断裂与重排、中间体和过渡态的产生、反应过程中的链式反应及引起有效链反应的中间体等，探索含能材料在极端高压下的爆轰分解机理。本项目的研究将对炸药性能标定、新型钝感炸药的设计研制及炸药安全性和有效性评估等具有一定的理论指导意义。

从微观层面认识典型含能材料在极端条件下的分解机理及物理性能，是现代爆轰物理、冲击波物理、高压凝聚态物理等多学科领域共同关注的重要科学问题之一。 本项目主要研究了典型含能材料固相硝基甲烷（CH3NO2）触发分解机制和高应变率下物性变化，及环三亚甲基三硝胺（RDX）的结构相变。我们的研究结果表明：高应变率下C-N键的断裂是引起固相硝基甲烷触发分解的主要原因。初始分解反应路径涉及到C-N键的断裂和分子间质子转移，反应过程中有H2O, NO, NO2, HONO产物生成且涉及双分子反应。另外，高应变率下固相硝基甲烷的结构研究发现：低压下，C-N键的变化对硝基甲烷的稳定性影响较大，而高压下，受C-H键的变化影响较大，正是由于这些原因，使得硝基甲烷分子在高应变率下的不稳定性增加，从而可能使其更易形成热点进而导致其分解或爆炸。高应变率下的力学和电子性质研究表明：固相硝基甲烷表现出较好的塑性、柔性和延展性；常压下具有间接带隙，随着压强的增加带宽增大，带隙减小。此外，我们还对极端条件下RDX的物性进行了探讨。本项目的研究为提高含能材料在外界环境条件下的力学稳定性提供理论指导，对含能材料的设计和研制具有一定的理论意义。