Dynamics of the O(3P) + CHD3(vCH = 0,1) reactions on an accurate ab initio potential energy surface

• Authors: Gábor Czakó, Eötvös University; Joel Bowman, Emory University
• Journal Title: Proceedings of the National Academy of Sciences
• Volume: Volume 109, Number 21
• Publisher: National Academy of Sciences | 2012-05-22, Pages 7997-8001
• Type of Work: Article | Final Publisher PDF
• Publisher DOI: http://doi.org/10.1073/pnas.1202307109
• Subjects: Chemistry, General
• Keywords: mode-specific dynamics; reactive scattering computations; state-to-state dynamics; permutationally invariant potential energy surfaces; benchmark ab initio data

Abstract

Recent experimental and theoretical studies on the dynamics of the reactions of methane with F and Cl atoms have modified our understanding of mode-selective chemical reactivity. The O + methane reaction is also an important candidate to extend our knowledge on the rules of reactivity. Here, we report a unique full-dimensional ab initio potential energy surface for the O(3P) + methane reaction, which opens the door for accurate dynamics calculations using this surface. Quasiclassical trajectory calculations of the angular and vibrational distributions for the ground state and CH stretching excited O + CHD3(v1 = 0,1) → OH + CD3 reactions are in excellent agreement with the experiment. Our theory confirms what was proposed experimentally: The mechanistic origin of the vibrational enhancement is that the CH-stretching excitation enlarges the reactive cone of acceptance.