Accurate nonadiabatic couplings for H3: Application to predissociation

We report the results of an ab initio calculation, using analytic techniques, of nonadiabatic couplings for ${\mathrm{H}}_3$ between the degenerate ${}^2{E}^{\prime }$ ground state and the ${\text{2s(}}^2{A}_1^{\prime }\mathrm{),}$ ${\text{3s(}}^2{A}_1^{\prime })$ and ${\text{3p(}}^2{E}^{\prime })$ Rydberg states. The calculations employed extensive correlated wave functions that accurately reproduced the energy levels of these states. We have used these couplings as input to a two-dimensional wave packet calculation of dissociation dynamics in order to predict the predissociation lifetimes and final state vibrational distributions produced by the predissociation. A significant isotope effect is found in the final vibrational distributions produced from ${\mathrm{H}}_3$ and ${\mathrm{D}}_3$ predissociation.