飞秒激光烧蚀含能材料的分子动力学模拟

为了得到飞秒激光侵蚀(FLA)1, 3二硝基甲苯(简称DNB，分子式：C₆H₄N₂O₄)，六硝基六氮杂异伍兹烷(简称CL20，分子式：C₆H₆N₁₂O₁₂)和CL20/DNB共晶系统的物理和化学响应过程，本文采用ReaxFF/lg反应力场对其过程进行模拟。计算结果表明，CL20/DNB系统的温度和压力在飞秒激光加载过程中出现阶跃，激光加载过程后系统有一个冷却过程，然后系统的温度和压力逐渐升高达到最大值并维持平衡。研究发现，在此过程中CL20和CL20/DNB系统触发反应均为CL20分子中的N―NO₂断裂。CL20系统的分解速率大于CL20/DNB共晶系统，这可能是因为共晶系统在反应初期具有大量的DNB分子以及分解产物中含有比较稳定的苯环减少了CL20及其产物之间的有效碰撞。

Molecular Dynamics Simulations of Femtosecond Laser Ablation of Energetic Materials

To understand the physical and chemical responses of energetic materials, such as 1, 3-dinitrobenzene (DNB, C₆H₄N₂O₄), hexanitrohexaazaisowurtzitane (CL20, C₆H₆N₁₂O₁₂), and CL20/DNB co-crystal, to femtosecond laser ablation (FLA), their molecular reaction dynamics have been investigated using the ReaxFF/ lg force field. The computational results indicate that the temperature and pressure of the CL20/DNB system jump during FLA. In particular, the temperature and pressure gradually reach their maxima following an initial cooling process. N―NO₂ bond breaking of the CL20 molecule triggers the reactions for both the CL20 and CL20/ DNB systems. However, the CL20 system prevails the CL20/DNB co-crystal in the decomposition rate simply because coexistence of DNB molecules in the mixture and generated decomposition products containing benzene rings greatly reduce the effective collision probability between CL20 and the products.