A 3-DIMENSIONAL QUANTUM-MECHANICAL THEORY TO TREAT TETRA-ATOM REACTIONS - STATE-TO-STATE DRESS SECTIONS FOR THE H-2-]H2O+H PROCESS(OH)

A quantum mechanical approach to treat diatom-diatom exchange processe s of the type AB+CD-->ABC+D is presented. The approach is based on thr ee types of wave functions psi(0 nu), psi(0 lambda) and chi, where the first two are (asymptotic) elastic distorted wave functions for the t wo arrangement channels nu and lambda, and chi is a short range (squar e integrable) wave function describing the system in the dose interact ion region. The functions psi(0 nu) and psi(0 lambda) are presented wi thin the j(Z) approximation, and to calculate chi, a perturbative-type Schrodinger equation which contains negative imaginary potentials (to form absorbing boundary conditions) is solved. The variationally stab le solution is obtained employing Gaussians and local adiabatic basis sets. The actual calculation of chi is done employing the quasibreathi ng sphere model, where the relevant angular coordinates are selected. randomly (about 50 sets like that were used) employing a Monte Carlo a pproach. With this approach, most detailed state-to-state cross sectio ns were calculated for the reaction H-2(n(1)=0, j(1)=0)+OH(n(2)=0, j(2 )=0)-->H2O(upsilon ($) over bar j upsilon K Omega(K))+H, where (upsilo n ($) over bar j upsilon) are the usual vibrational-bending states of the water molecule, and K and Omega(K) are, respectively, the overall rotational quantum number and the corresponding magnetic component. Th e results were compared with those due to other treatments and with ex periment.