A phase-space method for arbitrary bimolecular gas-phase reactions: Application to the CH3CHO+HOand CH3OOH+HOreactions

摘要

A new method based upon phase-space methods presented in Ref. [1] (Gross, A.; Mikkelsen, K. V, Stockwell, W. R. Int J Quantum Chem 2001, accepted) has been tested on the reactions CH3CHO + HO --> CH3CO + H2O and CH3OOH + HO --> products. The method has been used to calculate cross sections, and rate constants in the temperature range 200-550 K. The method requires knowledge of the system's reaction and product channels for the interacting species, the vibrational frequencies, the moments of inertia, and the potential energies of the molecules in their ground state equilibrium configuration. Furthermore, the long-range potential between the reactant and product species is required. Due to the lack of experimentally determined spectroscopic data and potential energies for the reactants and products, these values have been calculated using electronic structure theory. We have used the many-body second-order Moller Plesset perturbation theory (MP2) for the treatment of electron correlation in the molecules, together with two different Gaussian-type orbital (GTO) basis sets 6-31G and 6-31G*. The calculated rates are compared with the experimental data estimated earlier elsewhere. On the basis of our limited tests, the method appears to yield rate constants that are within a factor of 10-25 at 300 K of the true value, which is much more accurate than currently used empirical estimation methods. (C) 2001 John Wiley & Sons, Inc. [References: 43]