engleski

Reaction-path and dual-level dynamics of hydroxyl radical reaction with dimethyl sulfide

Variational transition state theory, multidimensional semiclassical tunneling calculations, and dual-level direct dynamics approach were used to estimate reaction rate constants for dimethylsulfide reaction with hydroxyl radical. Interpolated variational transition state theory based on ab initio reaction path calculated at MP2/6-31+G(d,p) level was corrected with energetics calculated at MP2/6-311++G(2df,2pd) level and augumented with small-curvature tunneling calculations. Direct dynamics was based on semiempirical PM3 hamiltonian parametrized for this specific interactions and augumented with large curvature tunneling correction. Calculated thermal rate constants are in a good agreement with experimental results. Vibrational-mode correlation analysis was carried out, i.e. characters of vibrational modes were identified as a function of reaction coordinate s. Statistical diabatic model was used to provide qualitative analysis on the possible vibrational-state specific chemistry of this reaction. Significant enhancement of reaction rates is predicted for the excitation of the C-H stretching mode.

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