Rate coefficients and kinetic isotope effects of the X + CH[subscript 4] → CH[subscript 3] + HX (X = H, D, Mu) reactions from ring polymer molecular dynamics
Author(s)Li, Yongle; Suleimanov, Yury V.; Li, Jun; Green, William H.; Guo, Hua
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The thermal rate coefficients and kinetic isotope effects have been calculated using ring polymer molecular dynamics (RPMD) for the prototypical reactions between methane and several hydrogen isotopes (H, D, and Mu). The excellent agreement with the theoretical rate coefficients of the H + CH[subscript 4] reaction obtained previously from a multi-configuration time-dependent Hartree calculation on the same potential energy surface provides strong evidence for the accuracy of the RPMD approach. These quantum mechanical rate coefficients are also in good agreement with the results obtained previously using the transition-state theory with semi-classical tunneling corrections for the H/D + CH[subscript 4] reactions. However, it is shown that the RPMD rate coefficients for the ultralight Mu reaction with CH[subscript 4] are significantly smaller than the experimental data, presumably suggesting inaccuracies in the potential energy surface and/or experimental errors. Significant discrepancies between the RPMD and transition-state theory results have also been found for this challenging system.
DepartmentMassachusetts Institute of Technology. Department of Chemical Engineering
The Journal of Chemical Physics
American Institute of Physics (AIP)
Li, Yongle, Yury V. Suleimanov, Jun Li, William H. Green, and Hua Guo. “Rate Coefficients and Kinetic Isotope Effects of the X + CH[subscript 4] → CH[subscript 3] + HX (X = H, D, Mu) Reactions from Ring Polymer Molecular Dynamics.” The Journal of Chemical Physics 138, no. 9 (2013): 094307.
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