QUANTUM CALCULATION OF THE RECOMBINATION RATE-CONSTANT OF H-]HCO(CO)

The rate constant for the recombination reaction H + CO + M --> HCO M is obtained at four temperatures as a function of the collision freq uency using a theory recently proposed by Miller [Miller, W. H. J. Phy s. Chem. 1995, 99, 12387]. This theory combines the flux-flux correlat ion function with the classical strong collision assumption to obtain the recombination rate constant as a function of the collision frequen cy. The expression for the rate constant is evaluated in a basis of co mplex L(2) eigenfunctions of a complex Hamiltonian, given by the real Hamiltonian for the nonrotating HCO system (J = 0), plus an absorbing potential in the asymptotic potential. The J-shifting approximation is used to obtain the rate constant for non-zero J. The flux-flux correl ation function is evaluated at several dividing surfaces, which define the boundary of the complex, and only a fairly minor dependence on th is surface is found at low temperatures, but a more substantial depend ence is found at high T. The results are compared with those of the st andard Lindemann theory and in the low-pressure region with the low-pr essure limit of the Lindemann theory. The calculated results are compa red with experiment at room temperature, with Ar as the buffer gas, an d can be made to agree well with experiment if the total stabilization collision cross section is about 15 bohr(2).