Knowledge Bank

Transition state theroy (TST), quasiclassical trajectories (QCT), and exact quantum (EQ) dynamics have been used to characterize the rate constants of $O(3P)+H2$ and its isotopic analogues. Two different potential energy surface have been used. The first is a colinear ab initio POLCI surface which incorporates the zero point energy for the bending vibration. The second is the Johnson and Winter LEPS surface. TST, QCT, and EQ calculations on the collinear portions of each surface have resulted in collinear transmission coefficients which then modify the fully dimensional TST at the calculated saddle point. For the POLCI surface the bending degree of freedom includes the Renner-Teller effect. The resulting POLCI rate constants are extensively and favorably compared to experiment. The LEPS rate constants in terms of isotope effects are compared to fully dimensional QCT and distorted wave quantum rate constants. The fully dimensional QCT isotope effects for HD are anomalously high and suggest fundamental differences in the way classical and quantum dynamics treats bending degrees of freedom along the reaction path.