title: Thermal Rate Constants for the O(3P) + CH4→ OH + CH3Reaction: The Effects of Quantum Tunneling and Potential Energy Barrier Shape.
abstract: The rate constants and kinetic isotope effects for the O(3P) + CH4reaction have been investigated with the quantum instanton method in full dimensionality. The calculated rate constants are in good agreement with the experimental values above 400 K, below which the measured values are scattered. Compared to other theoretical approaches, the quantum instanton method predicts the largest quantum tunneling effect, so it gives the largest rate constants at low temperatures. The calculated kinetic isotope effects are always much larger than 1 and increase with decreasing temperature, due to the zero-point energy and quantum tunneling. Our calculations on different potential energy surfaces demonstrate that the potential energy barrier shape dominates the magnitude of quantum tunneling and has a great effect on the kinetic isotope effect.
authors.affiliation: College of Science, Northwest A&F University , Yangling, 712100 Shaanxi Province, P. R. China.
authors.forename: Huali
authors.initials: H
authors.lastname: Zhao
authors.affiliation: College of Science, Northwest A&F University , Yangling, 712100 Shaanxi Province, P. R. China.
authors.forename: Wenji
authors.initials: W
authors.lastname: Wang
authors.affiliation: State Key Laboratory for Physical Chemistry of Solid Surfaces and Fujian Provincial Key Lab of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen 361005, P. R. China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhao