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Theoretical Studies of Polyatomic Reaction Dynamics

Donghui ZHANG
Dalian Institute of Chemical Physics, CAS

In this talk, I will present some of our recent work on theoretical studies of the H/F/O(1D)+CH4 and H+SiH4 reactions. For the H/F+CH4 and H+SiH4 reactions, accurate potential energy surfaces for these systems are constructed using neural network fitting method. They are found to be considerably more accurate than existing potential energy surfaces fitted by using permutation invariant polynomials. High dimensional quantum reactive scattering calculations were performed to obtain final state resolved integral and differential cross sections for these reactions. Comparisons between theory and experiment reveal that theory now is capable of producing dynamical information for these polyatomic reactions rather reliably. While for the O(1D)+CH4 reaction, a global full dimensional potential energy surface was constructed using permutation invariant polynomial fitting due to huge number of ab initio energies included. The deep well in the system and multiple channel nature of the reaction make quantum dynamics calculations, even under reduced dimensionality approximation, infeasible. Consequently, we carried out extensive quasiclassical trajectory calculations on the reaction which revealed a new reaction mechanism for this reaction.