New ab initio potential energy surface and quantum dynamics of the reaction H(2S) + NH(X3Σ-) → N(4S) + H2.

State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
The Journal of Chemical Physics (Impact Factor: 3.12). 09/2011; 135(10):104314. DOI: 10.1063/1.3636113
Source: PubMed

ABSTRACT A new global potential energy surface is reported for the ground state ((4)A(")) of the reaction H((2)S) + NH(X(3)Σ(-)) → N((4)S) + H(2) from a set of accurate ab initio data, which were computed using the multi-reference configuration interaction with a basis set of aug-cc-pV5Z. The many-body expansion and neural network methods have been used to construct the new potential energy surface. The topographical features of the new global potential energy surface are presented. The predicted barrier height is lower than previous theoretical estimates and the heat of reaction with zero-point energy is closer to experimental results. The quantum reactive scattering dynamics calculation was carried out over a range of collision energies (0-1.0 eV) on the new potential energy surface. The reaction probabilities, integral cross-section, and rate constants for the title reaction were calculated. The calculated rate constants are in excellent agreement with the available experimental results.

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    ABSTRACT: The stereodynamics and reaction mechanism of the H'(2S) + NH (X3Σ-) → N(4S) + H2 reaction are thoroughly studied at collision energies in the 0.1 eV-1.0 eV range using the quasiclassical trajectory (QCT) on the ground 4A″ potential energy surface (PES). The distributions of vector correlations between products and reagents P(θr), P(φr) and P(θr, φr) are presented and discussed. The results indicate that product rotational angular momentum j' is not only aligned, but also oriented along the direction perpendicular to the scattering plane; further, the product H2 presents different rotational polarization behaviors for different collision energies. Furthermore, four polarization-dependent differential cross sections (PDDCSs) of the product H2 are also calculated at different collision energies. The reaction mechanism is analyzed based on the stereodynamics properties. It is found that the abstraction mechanism is appropriate for the title reaction.