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High quality research in physical chemistry, chemical physics and biophysical chemistry.
Invited Article
Phys. Chem. Chem. Phys., 2006, 8, 917 - 925, DOI: 10.1039/b514563p
Quantum reactive scattering of H + hydrocarbon reactions
Boutheļna Kerkeni and David C. Clary
A practical quantum-dynamical method is described for predicting accurate rate constants for general chemical reactions. The ab initio potential energy surfaces for these reactions can be built from a minimal number of grid points (average of 50 points) and expressed in terms of analytical functionals. All the degrees of freedom except the breaking and forming bonds are optimised using the MP2 method with a cc-pVTZ basis set. Single point energies are calculated on the optimised geometries at the CCSD(T) level of theory with the same basis set. The dynamics of these reactions occur on effective reduced dimensionality hyper-surfaces accounting for the zero-point energy of the optimised degrees of freedom. Bonds being broken and formed are treated with explicit hyperspherical time independent quantum dynamics. Application of the method to the H + CH4
H2+ CH3, H + C2H6 H2+ C2H5, H + C3H8 H2+n-C3H7/H2+i-C3H7 and H + CH3OH H2+ CH3O/H2+ CH2OH reactions illustrate the potential of the approach in predicting rate constants, kinetic isotope effects and branching ratios. All studied reactions exhibit large quantum tunneling in the rate constants at lower temperatures. These quantum calculations compare well with the experimental results.
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