Time-dependent Quantum Scattering Approach To The Reaction H+S₂

Over the past decade, some significant achievements for chemical kineticscalculations have been made. Theoretical and experimental studies of chemicalreactions have also been developed into the molecular level. Especially, quantumscattering theory of the dynamics calculations of multi-atom reaction is verysuccessful. The time-dependent quantum scattering theory is more accurate than theclassical and quasi-classical method, and is more efficient than time-dependentquantum method. Adopting this method, many reactions are studied deeply in thestate-state level. Compared with the calculation results by other methods andexperimental results, time-dependent method is gradually showing a great superiority.The kernel problem of time-dependent quantum method is how to solve the timedependent Schr dinger equation, and the key ingredient is to propagate the wavepacket with time. Compared with other wave packet propagation methods, Chebyshevapproach is more effective. Especially, it can reduce the computational cost of theinteraction between the Hamiltonian and wave function for the reaction with adeep-well.HX2(X=O, S, etc.) plays an important role in atmospheric chemistry andcombustion chemistry. For example, potential energy surface of HS2has the followingfeatures:(1) There is a deep potential well in the reaction path;(2) The energy ofproduct is higher than that of the reactant, and the reaction is endothermic. In order tounderstand the stability of HS2in the atmosphere, a lot of studies have been carriedout on the structural and spectroscopic constants. However, few work toward itsdynamics calculations has been reported. Therefore, the dynamics studies of the H+X2is worth making.In this thesis, we have employed the method of time-dependent theory to study the three-dimensional dynamical properties of the H+S2. This thesis is organized asfollows. The basic content of the molecular reaction dynamics is introduced in sectionone. The basic theories of time-dependent are presented in Section two. The dynamicscalculations of the atomic and molecular reaction are described in Section three andfour. The conclusions of the paper are gathered in Section five.Among of the five sections, the fourth section is our main work during the periodof postgraduate. Firstly, the feature of the reaction probabilities and threshold energyare analyzed. Secondly, we studied the integral cross sections of the system and theeffect of deep potential well. Finally, the temperature dependence of thermal rateconstants is shown. For this typical endothermic reaction, we get some importantconclusions.