## Abstract

A previous trajectory study of the dissociation of Cl ^{-}⋯CH_{3}Cl complexes formed by Cl^{-}+CH _{3}Cl association is further analyzed to determine (1) the relationship between classical and quantum Rice-Ramsperger-Kassel-Marcus (RRKM) rate constants for Cl^{-}⋯CH_{3}Cl→Cl^{-}+CH _{3}Cl dissociation; (2) the importance of anharmonicity in calculating the RRKM dissociation rate constant; (3) the role of angular momentum in interpreting the trajectory distribution N(t)/N(0) of Cl ^{-}⋯CH_{3}Cl complexes versus time; and (4) the pressure-dependent collision-averaged rate constant k(ω,E) for Cl ^{-}⋯CH_{3}Cl dissociation. It is found that only the low-frequency intermolecular modes of Cl^{-}⋯CH_{3}Cl are initially excited by Cl^{-}+CH_{3}Cl association. Classical and quantum RRKM rate constants for dissociation of this intermolecular complex are in excellent agreement. Anharmonicity lowers the rate constant by a factor of 4-8 from its harmonic value. The dissociation rate for the long-time tail of the trajectory N(t)/N(0) distribution is much smaller than predicted by a RRKM model, which accurately treats angular momentum. It is suggested that the long-lived trajectories may arise from motion on vague tori. The trajectory collision-averaged rate constant k(ω,E) is in agreement with an experimental study at 300 K.

Original language | English |
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Pages (from-to) | 5626-5635 |

Number of pages | 10 |

Journal | The Journal of Chemical Physics |

Volume | 102 |

Issue number | 14 |

DOIs | |

State | Published - 1995 |