On the electronic nonadiabatic effects in the H+H2 reaction dynamics

The effects of electronic nonadiabatic coupling on the dynamics of the most fundamental H + H-2 reaction are studied in this paper. A time-dependent wave packet approach along with the double many body expansion potential energy surfaces of the system is employed in the present investigation. The effect of reagent rotations and vibrations on the reactivity is mainly studied in the paper employing the coupled states approximation. Initial state-selected and energy resolved reaction probabilities have been reported for reagent, H2 in its (v = 0, j = 0-10) and (v = 0-10, j = 0) states, respectively, upto the three-body dissociation energy of H-3 (similar to 4.7 eV). Calculations are performed both with and without surface coupling and the results are compared. Integral reaction cross sections have been calculated from the reaction probabilities. All partial wave contributions upto the total angular momentum, J = 50 are included to obtain converged integral reaction cross sections. Analysis of the reaction probability and reaction cross section data shows that the nonadiabatic effects are insignificant at small values of j and v, which become more pronounced with an increase of the latter quantities. Electronic nonadiabatic effects appear to be more important in the reaction dynamics of rotationally excited H-2.