Time-dependent Wave-packet Approach To The Photondissociation Of Small Molecules

The photoionization and photodissociation of molecules in strong laser field have attracted much interest in recent years. When an atom or molecule is subjected to an intense external field, some new phenomena will appear. The wave-packet dynamics is an important branch of physical chemistry. In the molecular collision study, it has been proved to be very effective. Its theoretical framework 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 and but also the quantum precision. In addition, the wave-packet method is very applicable in dealing with the evolution of the system.Recently, in the theoretical research fields of photodissociation dynamical behavior, much attention is focused on small molecules. In the theoretical treatment of single molecule dynamics, one spatial dimension and two-state system is the simplest one. The introduction of the appropriate computational approaches to the dynamics of wave-packets on this system is very important for understanding the treatment of complex systems. Besides, it has theoretical and practical instruction for chemical reaction controlling.In this thesis, we study the photodissociation dynamic of HCl molecule. The"split operator-Fourier transform"method of quantum mechanics time-dependent wave- packet propagation is employed in the simulation process. The main work is given as follows:(1) Firstly, we have solved the time-dependent Schr(?)dinger equation by using Fourier grid Hamiltonian method, and obtain the eigenfunction of HCl for the different ground vibrational state.(2) The wave-packet is propagated using the"split operator-Fourier transform"method.(3) The photodissociation cross section for HCl molecule of the different initial vibrational levels of X 1∑+( v = 0, v = 1, v = 2 and v = 3) ground state to A 1∏state in a wide range of photon energy is obtained from a single calculation by the Fourier transformation of the autocorrelation function over time.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 introduces the photodissociation dynamics species. In chapter three, the theoretical and computational methods used in the simulation process are presented. In chapter four, the theoretical model of HCl photodissociation dynamics is given. The last chapter is our conclusion.