Quantum Reaction Dynamics Study Of Vibrational Excitation Effects On The O+CHD₃/CD₄â†'OH/OD+CD₃and Cl+CHD₃/CD₄â†'HCl/DCl+CD₃Reactions

Molecular reaction dynamics is the forefront of physical chemistry research. It is thestudy of molecular level mechanism of elementary chemical and physical processes. In recentyears, with the enhancement of computer calculating capacity and the development ofquantum scattering theory, applying quantum theory to studying molecular reaction dynamicsrules has became an important subject. Enormous progress has been made on the research ofpolyatomic reaction dynamics. Accurate full quantum calculations can be made currently onreaction systems with four or less atoms. However, what chemistry concerns most are thesystems which contain more than four atoms. With the increase of atomic amount and thedegrees of freedom, it becomes more and more difficult to research. Therefore, it is necessaryto explore and develop new theoretical models and calculation method for polyatomicsystems. So far, some theoretical models and reduced dimensional methods have beenprovided.In this paper, a quantum reactive dynamics, six-degrees-of-freedom, time-dependentwave packet method is employed to study Energy efficiency in surmounting the reactionenergy barrier and vibrational enhancement on reactivity of the O+CHD3/CD4â†'OH/OD+CD3and Cl+CHD3/CD4â†'HCl/DCl+CD3reactions.For the O+CD4â†'OD+CD3reaction system, the calculations show that all thevibrational excitations of CD4enhance reactivity, which agrees with quasi-classical trajectoryresults. However, the experimental observation finds that the bending excitation suppressesreactivity. Our finding contradicts it here. The present study also reveals that translationalenergy, in general, plays a more efficient role in the reactivity than vibrational energy;however, vibrational energy is slightly more effective than translational energy at highercollision energy. For O+CHD3â†'OH+CD3reaction, the stretching and bending excitationsof CHD3enhance the reaction, but the umbrella motion hinders reactivity. The calculated excitation functions agree well with the experiment’s results.In the other hand, for the Cl+CHD3/CD4â†'HCl/DCl+CD3reactions, all thevibrational excitations of CHD3/CD4enhance the reaction reactivity and the C-H/C-Dsymmetric stretching motions have the biggest impact on the reactivity. For these twolate-barrier reactions Cl+CHD3/CD4, both vibrational energies are more effective to promotethe reactions than the translational energies except at very low collision energies. In otherwords, except at very low collision energies, the Polanyi rules can still be extended to thesetwo polyatomic reactions.This paper is divided into six chapters. The first chapter is introduction, which brieflyintroduces the development of molecular reaction dynamics and time-dependent wavepacketmethod. Chapter two presents the basic theory and calculation method of wavepacketdynamics. Chapter three introduces the six-degrees-of-freedom reduced dimensional model.In chapter four, we apply our model to O+CHD3/CD4â†'OH/OD+CD3systems. Then, weshow the results for Cl+CHD3/CD4â†'HCl/DCl+CD3systems in chapter five. The lastchapter is conclusions.