The Liner Entropy By Intense Laser Pulses In Triatomic Molecules

In this paper, the dynamical Lie algebraic method of linear triatomic molecule in the laser field in the time-evolution of nature. Theoretical studies of molecules in the laser field evolution is currently a hot topic in the field of molecular dynamics.Molecular dynamics is a combination of an emerging interdisciplinary physics, mathematics and chemistry technology. It is a set of molecular simulation methods, the methods rely on Newtonian mechanics to simulate the movement of the molec-ular system, the samples were collected in the ensemble constituted by the different states of the molecular system in order to calculate the configuration integral of the system, and configuration integral based on the results further calculate ther-modynamic quantities and other macroscopic properties of the system. Molecular dynamics is the relationship between microscopic structure and macroscopic proper-ties of the molecules studied, while the entropy of its structure and characteristics of the molecules are closely linked. Using ultrashort pulses of infrared laser can make a strong bond breaking of molecular weak bond remains unchanged, in order to achieve bond-selective dissociation of molecules. And there have been similar experiment reported, these experimental facts related to the interaction with the molecular nonlinear optical properties of non-adiabatic effects and the vibrational modes. Shows that the molecular and the laser field interaction significance.Non-harmonic vibration of the vibration of molecules in intense laser field, due to the strong external field, so that the general perturbation theory fails, the Schrodinger equation for solving such problems too computationally intensive and difficult. The late1970s to early1980s, with the advent of large high-speed electron-ic computer, the application of efficient numerical simulation method, rapid research and development of molecular entropy theory, the emergence of a variety of meth-ods, including the theory of Lie algebras. The theoretical description of quantum, classical and semi-classical description. Studies have shown that the semi-classical and quantum description of strong-field case is equivalent, in the semi-classical de- scription of the characterization of molecular system is quantized field, the classical form ofLie algebra is a mathematical concept, Marius Sophus Lie, Norwegian math-ematician, introduced in the late19th century study continuous transformation group, it is closely related to the Lie, Lie algebra, the term is introduced by Weyl in1934. Lie group and Lie algebra theory is in the process of research differential equation first proposed, the method was introduced with the establishment of the matrix mechanics, and are widely used in elementary particle quantum mechanics in the1950s, eighties Iachello and Levine, who will be the Lie algebraic approach to the field of nuclear physics successfully transplanted to the field of molecular physics. With the passage of time, the position of the Lie algebras in mathematics and classical mechanics and quantum mechanics on the rise. Lie algebra of the theory continue to improve and develop its theory and method has penetrated into many areas of mathematics and theoretical physics. In recent years, including the application of the dynamical Lie algebraic method development, should be widely used in research in the field of molecular physics, nuclear physics and quantum optics, and the success and potential energy of vibration excitation of polyatomic molecules face the problem studied.In this paper, a linear triatomic molecule and the interaction of the laser field in the molecular evolution of the linear entropy, discussed the impact of the initial state of the system of molecular linear entropy. Entropy of the specific molecular evolution, the results show that the theoretical approach given in this article deal with molecular dynamics in strong field, can be further promoted. Only studied the evolution of the linear triatomic molecule entropy, if you consider other factors such as rotating, you can get a richer dynamic information, and can use this method to study the evolution of the atomic and molecular entropy for the further The work laid the theoretical foundation.The thesis is divided into four chapters:1. First chapter is the Review, introduced the concept and research and develop- ment status of the molecular entropy, focusing on the Lie algebraic method, and describes its strengths in research on this issue.2. Second chapter is theoretical basis, and describes the main theoretical con-cepts and formula derivation process, introduce a second non-harmonic oscil-lator model, this model gives the total Hamiltonian, the system time evolution operator expression, given the expression of entropy.3. Chapter Ⅲ study of the evolution of the entropy of linear triatomic molecules in intense laser fields. Focuses on how to use the numerical calculation to ob-tain the molecular entropy and its evolution, and the evolution of the entropy to make the corresponding analysis.4. Forth chapter is conclusion, given the results of the research work, the direc-tion of further development of theoretical methods and its application prospec-t.