Quasi-Classical Trajectory And Time-Dependent Wave Packet Dynamics For Triatomic Reaction

Molecular reaction dynamics has been an active research field in contemporary science, the commonly used theory research methods are the classical mechanics method, quasi-classical trajectory (QCT) method and quantum mechanical (QM) method. Firstly, the adiabatic dynamics properties, including scalar properties and vector properties, of Ba+HFâ†'BaF+H and O(1D)+HFâ†'OH+F(2P) have been studied using the QCT method. For Ba+HF system, the potential energy surfaces (PESs) is repulsive, the integral cross section has no threshold and rapidly increases with the collision energy increasing then slowly increases; the vibrational excitation of the reagent can promote the reaction, after H replaced by D and T, the highest vibration level of product molecules becomes smaller and the proportion of product with low vibration level is larger, the product change from the backward scattering to forward scattering, weaken the product rotation orientation, but has little impact on the product rotation alignment; the product rotation strongly aligned about the relative velocity of reactants as the result of HHL mass combination, the degree of backward scattering of product becomes srtonger, the product rotation alignment and orientation get weaker. For the O(1D)+HFâ†'H+F(2P) reaction on the l1A’ PES, the integral cross section and the product rotation alignment fator have been calculated, the effect of isotope substitution and the reagent rotation excitation on the stereodynamics properties have also been studied, it indicates that, owing to the deep noncollinear insertion HOF well, the angular momentum polarization of the product molecule is weak, the effects of isotope substitution and the reagent rotation excitation on stereodynamics are indistinctive. Later, we improve the QCT calculation procedure and take the F+OHâ†'HF+O reaction on the l3A" PES as an example to investigate the effect of the reactant alignment on the reaction probability and the polarization of the product. Finding that because the transition state and the reactants well vary with the θ(OHF) angle, the incident angle has a great impact on the reaction probability and stereodynamics of reaction, this work can not only reveal the dynamics of the chemical reaction from a new perspective but also provide some detail information of the PES.Secondly, due to the defects of QCT method itself: inability to properly treat the quantum mechanical zero-point energy and quantum tunneling, the QCT method and the quantum time-dependent wave packet method have both been used to study the adiabatic process of the He+D2+reaction. Because of the Feschbach resonances originating from the deep potential well in the He+D2+triatomic interaction region are significant, QCT is not reliable to study the dynamics of He+D2+reaction; the comparison between the CC and CS cross sections for ν=1and2reveals that the coriolis coupling significantly influence the trend and the value of the calculated cross sections, and the comparison between the CC and CS probabilities forj=0and1reveals that the coriolis coupling has something to do with the rotational quantum number of D2+Finally, the intersystem crossing effects in the O(3P2,1,0)+D2(ν=0,j=0) reaction have been studied using the time-dependent wave-packet method combining with an extended split operator scheme, the results have also been compared to the corresponding ones of O(3P)+H2system. It is found that the influence of spin-orbit on the total reaction cross sections of the two reactions is both insignificant, and the differences in non-adiabaticity between these two reaction systems are quite modest, however, these non-adiabatic effects can be reflected in the presence of some forward-scattering in the angular distribution for the product.