【作者】 徐会强；

【导师】 孟庆田；

【作者基本信息】 山东师范大学 ， 原子与分子物理， 2008， 硕士

【摘要】 分子反应动力学是从原子、分子层次出发研究化学反应微观动态和机理的科学,它的研究不仅可以阐明分子反应过程中各种瞬态物质的结构、性质和作用,还能通过对态-态反应动力学,以及对分子相干态之间作用的深入研究来阐明化学反应的内在规律。光解反应动力学是光化学的一部分,也是分子反应动力学的一个重要分支。作为分子反应动力学重要研究工具的含时波包动力学理论在分子物理和场与分子相互作用等研究领域也有着广泛的应用。含时波包法有许多优点,除了数值计算上的高效率外,该方法还为动力学研究提供了物理意义明确而直观的图像,它既具有经典的直观,又不乏量子力学的准确。本论文主要是基于Born-Oppenheimer近似,应用含时波包动力学方法研究了双原子分子—NaH光解的吸收截面,讨论了时间传播方法、势能面、初始波包对光解截面的影响,主要的研究内容和结果如下:首先在绝热近似下,利用傅立叶格点-哈密顿方法(FGH)求解含时薛定谔方程、劈裂算符方法作为波包传播方案计算了NaH分子从基态X 1∑+( v" = 0)跃迁到激发态B 1∏上的光解截面。为了研究不同的波包传播方案对NaH分子光解截面的影响,我们将计算结果与使用Chebyshev多项式展开方法得到的结果进行比较,结果表明这两种时间传播方案对总的光吸收截面的计算是等效的。其次,依据离解阈能的实验值,我们将势能曲线进行了重置,然后将计算结果与Bhattacharjee等人的结果进行比较,得到了影响光解截面的关键因素。最后选取了四个不同的振动态( v " = 0、1、2、3)作为初始波包,研究了不同的初始波包对光解截面的影响。论文共分为五章。第一章为综述,主要介绍了分子反应动力学的基本理论及波包动力学方法的发展。第二章对光解动力学进行了简介。第三章介绍了研究光解动力学所用到的理论和方法。第四章,主要介绍了研究过程和计算结果,并讨论了时间传播方法、势能面、初始波包对光解截面的影响。第五章是本论文的结束语,简要地对本论文进行了总结。更多还原

【Abstract】 Molecular reaction dynamics studies the microcosmic dynamics and principle of the chemical reaction based on atomic and molecular level. It can elucidate not only structures, characters and functions of all kinds of transient species during reaction, but also intrinsic law of chemical reaction from the research on state-to-state reaction dynamics and the interaction of coherent states. Photodissociation is at the heart of photochemistry, and it is also an important embranchment in molecular reaction dynamics.The time-denpendet wave-packet dynamics as the tool of molecular reaction dynamics research has many applications in molecular physics and the field-matter interaction systems. The time-dependent wave-packet method is very attractive. Besides the numerical efficiency, time-dependent wave-packet method is conceptually simple. It provides not only a classical-like interpretation,but also the quantum precision.This thesis studies the absorption cross section of diatomic molecule-NaH molecule during its photodissociation process on the basis of the Born-Oppenheimer approximation theory. The influence of the different propagation methods, the different potential energe curves, as well as the different initial wave-packets to the absorption cross section is discussed. The main contents and results are presented as follows.First, this thesis calculates the absorption cross section of NaH molecule from ground state X 1∑+( v" = 0) to B 1∏using Fourier grid Hamiltonian method to solve the time-dependent Schr?dinger equation and using split operator method as a wave-packet propagation scheme on the basis of the adiabatic approximation theory. In order to study the effects of different wave-packet propagation scheme on photodissociation cross section of NaH, The results obtained by plit-operator method was compared with those obtained by the Chebyshev propagation scheme. The results indicate that the two schemes are equivalent in calculate the total absorption cross section. Then, according to the experimental result of the threshold energe, the potential energe curves were rearranged, the results we obtained were compaired with the rusults gived by Bhattacharjee et al. , the key influence factor of photodissociation cross section was obtained. Last, Four different vibrational states ( v " = 0,1,2,3)were taken as initial wave-packets to investagate the influence to the photodissociation cross section.This submitted work is divided into five chapters. The first chapter is the introduction, which briefly discusses the basic theory of molecular reaction dynamics. Also presented is the development of the time-dependent wave-packet method. Chapter two introducts the development and significance of photodissociation dynamics. In chapter three, the theoretical and computational methods used in photodissociation dynamics are presented. The research process and the results are given particularly and the influence of different propagation methods、the different potential energe curves、the different initial wave-packets on the photodissociation cross section are disscussed in the fourth chapter. The summary and the prospect are represented in the last chapter.更多还原