【作者】 陆裕平；

【导师】 朱俊；

【作者基本信息】 四川大学 ， 原子与分子物理， 2005， 硕士

【摘要】 黑索金（RDX）是一种敏感高能优质炸药,同时也是宇航和导弹武器等推进系统所用的固体推进剂和炸药的主要成分。对RDX的结构及起爆和爆轰的复杂物理化学过程的研究不仅可以加强对其本身结构和性能的理解,而且对研制具有更好的起爆、燃烧及感度性能的推进剂和炸药的性能优异配方具有重要意义。另一方面,众所周知,主要由范德瓦尔斯作用引起的非键相互作用对理解气体、液体、固体以及其它凝聚态物质的结构和性能起着至关重要的作用。分子间相互作用势还是分子动力学模拟中所用经验势的一个重要组成部分。 因此,本论文首先利用从头算梯度修正密度泛函理论,在B3LYP/6-31G（d,p）水平上,计算了高能炸药RDX及其热解中间产物C₃H₆N₅O₄和NO₂等的电子结构、能量、键级和一些热力学性质,并在此基础上,计算了键离解能和反应速率常数。我们还分别从键级和键离解能角度,讨论了RDX的热解机理,利用两种方法分析得到的结果一致。结果表明主要的初始反应通道是从N-NO₂键的断裂开始的。在RDX中最弱键是其中的一个N-NO₂键,它的Mulliken键级和键离解能分别为0.1623和157.2718KJ/mol,所得结果与实验一致。 其次,利用含微扰三重修正的单、双激发耦合簇CCSD（T）理论,对Ar-N₂分子间相互作用势能面进行了从头算超分子计算。运用完全平衡修正方法校正基组重叠误差（BSSE）。计算结果表明:T-型结构是Ar-N₂体系最稳定的构型,其势阱深度D_e为12.40meV,对应的分子间平衡距离R_m是3.70（?）。计算得到的表征势能面的各项异性的值ΔR_m,ΔR₀和ΔD_e分别是0.56（?）,0.54（?）和2.68meV。与其他人的研究结果相比,我们计算的势能面与实验结果更趋一致。更多还原

【Abstract】 RDX, an important explosive with high characters and properties, is an energetic ingredient that is used in various solid propellants and explosives. Understanding its structure and the complex physicochemical process that underlie the combustion of this material can lead to method for modifying the propellant and explosive formulations in order to obtain better ignition, combustion, or sensitivity properties.On the other hand, it is well-known that the nonbonding interaction potentials, mainly resulting from van der Waals (vdW) interactions, play a crucial role to understand the structures and properties of gases, liquids, solids, as well as any other materials in condensed phase. It is also an important component of empirical potentials, which are often used in molecular dynamic simulations.In the work, we first calculate the electronic structures and properties of RDX molecule and its intermediate products formed during its decomposition process at B3LYP level using 6-31G(d, p) basis set. We present the geometrical parameters, energies, bond orders, thermochemestries and so on. Using those results, we also calculate the bond dissociation energies and rate constant of reaction for RDX and then study the decomposition mechanism of RDX from bond orders and bond dissociation energies two perspectives, respectively. Results show that the dominant initial reaction channel is the N-NO2 bond rupture, which has the weakest Mulliken bond order and bond dissociation energy for 0.1623 and 157.2718KJ/mol respectively. These are consistent with the experimental results.Secondly, the intermolecular interaction potentials of van der Waals Ar-N2 complex have been studied by ab initio calculations using the single and double excitation coupled cluster [CCSD(T)] theory with perturbative triples correction. The full counterpoise method is applied to correct the basis set superposition error (BSSE). It is found that the T-shaped structure is the most stable conformation with the well depth De of 12.40meV at the minimum distance Rm of 3.70A. The calculated anisotropic values for △Rm, △R0 and △De are 0.56A, 0.54A and 2.68meV, respectively. Compared with those obtained by others, our calculated PES seems to be in better agreement with experiments.Thirdly, the equilibrium structure and intermolecular interaction potentials of water dimer have been calculated using supermolecular many-body perturbation theory at the second-order to fourth-order level. The augmented correlation-consistent basis set aug-cc-pVTZ and the effective midbond functions {3s3p2dlflg} are employed. Basis superposition error is corrected by applying the counterpoise procedure. At the MP2 level with aug-cc-pVTZ basis set, the values of Ro-o and a slightly increase 0.02A and 0.19, respectively, while the magnitude of θ drops 0.013 on the CP-optimization geometry compared with the normal optimization geometry. The MP2 calculations with augmented correlation-consistent basis set combining with effective midbond functions predict the values of Ro-o, and △Ecp, for 2.93A and -4.86kcal/mol respectively, which are in better agreement with experiment. The discrete grid of calculated intermolecular interaction energies is fitted to exp-4.2 potential function. The agreement between the fitting and the ab initio results is excellent.更多还原