Quantum and quasiclassical dynamics of C(^(3)P)+H_(2)(^(1Σ_(g)^(+)))→H(^(2)S)+CH(^(2)Ⅱ)reaction:Coriolis coupling effects and stereodynamics

The dynamics of C+H_(2)→H+CH reaction is theoretically studied using the quasiclassical trajectory and quantum mechanical wave packet methods.The analysis of reaction probabilities,integral cross sections,and rate coefficients reveal the essential Coriolis coupling effects in the quantum mechanical wave packet calculations.The calculated polarizationdependent differential cross section,P(θ_(r))and P(Φ_(r))show that the j'of product rotational angular momentum is not only aligned along the y axis and the direction of the vector x+z,but also strongly oriented along the positive y axis.

Stereodynamics study of the exchange reaction O(~3P)+CH_4 →H+OCH_3

A new London-Eyring-Polanyi-Sato potential energy surface is employed in this work to study the stereo properties of the O （^3p） ＋ CH4 → H ＋ OCH3 reaction in its rovibrationally ground state using the quasiclassical trajectory method （QCT）. Our calculations are performed at a range of collision energies, Ec = 1.5 eV^-3.5 eV, and the excitation function obtained by the QCT method accords well with the experimental data. The product rotational polarization is calculated, and the product shows a strong rotational polarization in the centre-of-mass coordinate system. The orientation of the product rotational angular momenta is sensitive to the increase in collision energy, and the alignment of the product rotational angular momenta shows some of the properties of the heavy heavy-light mass combination reactions. In the isotopic substituted reaction study, when the H atoms in methane are replaced by D atoms, the rotational polarization is obviously reduced. The polarization-dependent differential cross section is also studied by this QCT calculation to provide detailed information about the rotational alignment and orientation of the product.

Stereodynamics in reaction O(~1D) + CH_4 →OH + CH_3

A theoretical study of the stereodynamics for reaction O(1D) + CH4→OH + CH3 has been carried out using the quasiclassical trajectory method(QCT) on a potential energy surface structured by Gonzalez et al. The integral cross sections(ICSs), differential cross sections(DCSs) and product rotational angular momentum polarization have been calculated. With the collision energy increasing, the ICS decreases. There is no threshold energy, because no barrier is found on the minimum energy path. The DCS results show that the backward and forward scatterings exist at the same time. With the collision energy increasing, the dominant rotation of the product changes from the right-handed direction to the left-handed direction in planes parallel to the scattering plane. In the isotopic effect study, the decrease of the mass factor weakens the polarization degree of the rotational angular momentum vectors of the products.

Influence of Early-staged Energy Barrier on Stereodynamics of Reaction of LiH(v=0, j=0)＋H → Li ＋ H2

Theoretical studies of stereodynamics for reaction LiH（v=0, j=0）＋H → Li＋H2 have been carried out with quasiclassical trajectory method on two potential energy surfaces（PESs） structured as W-PES and P-PES. The main difference of the two PESs is at fixed angle of Li--H--H from 110° to 180°. In this angle range, there is an early- staged energy barrier on the P-PES, but there is no barrier on the W-PES. Some studies have been done to explore the influence of the early-staged energy barrier on this exothermic reaction. Integral cross sections, differential cross sec- tions and product rotational angular momentum of the reaction have been calculated. When Ec〈0.48 eV, the do- minant influence of barrier is to restrain reacting. However, when Ec〉0.48 eV, the dominant influence of barrier is to promote reacting. The angular distribution of the product H2 is extremely forward on both the PESs, because the life- time of most complexes is short. Totally, the lifetime on the P-PES is longer than that on W-PES for the existence of the barrier. With the collision energy increasing, on the both PESs, the distribution of the direction of the product H2 angular momentum changed, and there is a trend that peak at （90°,270°） gets weaker and peak at （90°,90°） gets stronger. The energy barrier weakens the degree of the rotation alignment of the H2.