Quantum dynamics of the reaction of hydrogen atom with methane

Time-independent quantum scattering calculations on the H + CH4 --> H-2 + CH3 reaction have been performed by using a four-dimensional rotating bond umbrella (RBU) model, based on a modified potential energy surface of Espinosa-Garcia and Corchado. The new surface gives a vibrationally adiabatic ground state barrier height of 14.1 kcal/mol. Calculated thermal rate constants are in good agreement with the experimental results. At room temperature the rate constant obtained is 8.16 x 10(-19) cm(3) molec(-1) s(-1). It is found that the simple energy minimization approximation gives significantly small thermal rate constants for this reaction. (C) 2000 Elsevier Science B.V. All rights reserved.