6533b857fe1ef96bd12b4d14

RESEARCH PRODUCT

Ab Initio Study of the Mechanism and Thermochemistry of the Atmospheric Reaction NO + O3 → NO2 + O2

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The atmospheric reaction between NO and ozone has been investigated using ab initio methods. The structures of all reactants, products, intermediates, and transition states of reaction 1 have been optimized and characterized at the UMP2(full) level of theory. The 6-31G(d), 6-311G(d), and 6-311G(df) basis sets have also been used to calibrate the effect of the basis set functions on the optimized structures and energies of all stationary points. Finally, we have reoptimized at the UMP4(SDQ, full)/6-31G(d) and 6-311G(d) levels. The energetics of the reaction has been studied more accurately within the G2 and G2(MP2) schemes. Also, QCISD(T)/6-311G(d) single-point calculations have been performed by using UMP2(full)/6-31G(d), 6-311G(d), and 6-311G(df) geometries. The mechanism study of the NO + O3 → NO2 + O2 reaction has shown that the transition between reactants and products is not direct, but it proceeds along two transition states (TS1 and TS2) separated by the intermediate (A). There is also the possibil...