AP与HMX、RDX反应机理的理论研究及UA光致异构化反应的动力学模拟

【作者】 姜富灵；

【导师】 岳可芬； 翟高红；

【作者基本信息】 西北大学 ， 物理化学， 2010， 硕士

【摘要】 本论文的内容分为两部分,第一部分重点讨论高氯酸铵(AP)与含能材料奥克托金(HMX)及黑索金(RDX)混合后的裂解机理；第二部分利用半经典的电子-辐射-离子动力学(Semiclassical electron-radiation-ion dynamics, SERID)方法实时模拟咪唑丙烯酸(UA)光致异构化的动力学过程。第一章概述了分子热力学和动力学的理论基础,包括计算方法简介、过渡态理论、频率计算和热力学校正、IRC理论、半经典的电子-辐射-离子动力学(SERID)模拟以及SERID方法程序的实现。第二章主要讨论了AP分解后的小分子产物OH及OH-对HMX裂解的影响。计算发现,β-HMIX与NH3、ClO3结合后其N-NO2键解离能与HMX相比均变化不大,但一旦复合物裂解有NO2生成,生成的N02极易与NH3发生反应,放出大量热,从而可引发HMX的后续裂解反应；NO2易与HMX骨架环上亚甲基(-CH2-)中的H作用,“置换”出H而引发HMX的热解,从而改变了HMX的初始分解通道；OH对HMX的N-NO2键解离影响不大,而OH-与β-HMX结合后其N-NO2键解离能比β-HMX降低近200 kJ-mol-1,表明OH-对其裂解有明显的促进作用。此外,我们还计算了常压、4 MPa及6 MPa高压下P-HMX与NH3、ClO3形成复合物的N-NO2键解离能,发现高压环境不改变这些小分子对HMX初始裂解的影响。第三章介绍了酸性条件对RDX三种裂解方式的影响。计算发现H+对RDX的开环有明显的促进作用；H+接近RDX中的N原子形成RDX_HN后,更有利于断裂N02和HONO的消去,而接近RDX中的O原子形成RDX_HO对于两者的进行没有明显影响。第四章利用一种半经典非绝热动力学模拟方法—半经典的电子-辐射-离子动力学(SERID)实时模拟咪唑丙烯酸(UA)光致异构化的动力学过程。模拟发现,给定不同的激光流量和光子能量,UA由反式转化为顺式的路径不同,各轨道存在的时间也有所不同。最后,我们在CASSCF/MRPT2水平上用4-31G基组构造了绝热态的势能剖面图,其中CASSCF采用GAMESS量子化学程序包完成,而MRPT2的计算则是采用我们小组自主研发的基于图形酉群理论和空穴粒子对应的XIAN-CI程序包完成的。更多还原

【Abstract】 The dissertation can be divided into two parts. In One part, we focus on the effects of products of ammonium perchlorate (AP) on the initial pyrolysis of HMX、RDX. In the other part, by using a semiclassical nonadiabatic molecular dynamic simulation-a semiclassical electron-radiation-ion dynamic approach (SERID), we simulating dynamics of the photoisomerization process of urocanic acid.In chapter 1, we briefly show the theoretical background of molecular thermodynamics and molecular dynamics, including the introduction of calculation methods, transition state theory, the frequency calculation and thermodynamic correction, IRC theory, a semiclassical electron-radiation-ion dynamic approach (SERID) methods and the implementation of this program.In the second chapter, we report the effects of NH3、Cl03、NO2、OH and OH- on the initial pyrolysis of HMX. The results indicate that, there are trivial changes on the N-NO2 bond dissociation energies when P-HMX combines with NH3 or ClO3. However, once the complexes decompose, the product NO2 can react with NH3 more easily. This exothermic reaction may induce the subsequent pyrolysis process of HMX. NO2 can easily capture H of the methylene on the HMX ring, which will change the initial pyrolysis channel of HMX. The influence of OH is negligible. The N-NO2 bond dissociation energies of OH- complexes decrease about 200 kJ-mol-1, in comparison with that ofβ-HMX, which indicates that OH- can clearly promote the initial pyrolysis ofβ-HMX. We also obtained bond dissociation energies for N-NO2 in P-HMX and its complexes at Normal Pressure,4 MPa and 6 MPa. The high pressure has no influence on the effects of NH3 and ClO3 on the initial pyrolysis mechanism of HMX.The third chapter describes the effects of H+ on the three kinds of initial pyrolysis of RDX. Our calculation results showed that the H+ can significantly promote the initial thermal decomposition of C-N bond of RDX; We found that H+ induce the RDX to trigger the N-NO2 heterolysis and HONO elimination evidently when H+ approach the N of RDX, which, however, is influenced slightly when H+ approach the O of RDX.In the last chapter, by using a semiclassical electron-radiation-ion dynamic approach (SERID), we study the dynamics of photoisomerization process of urocanic acid. Through the simulation we find that the excited molecule decays to the electronic ground state through different radiationless pathways by given the different photon energy and laser pulses, and the life time of the tracks is also different. Finally, we calculate the potential energy curves with the CASSCF/MRPT2 method.更多还原