Quasiclassical Trajectory Study of the Reaction H2+OH->H2O+H. Comparison With Quantum Results

JULIANA PALMA; JULIÁN ECHAVE; DAVID C. CLARY

JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS I

The Royal Society of Chemistry

Año: 1997 vol. 93 p. 841 - 846

0300-9599

We report a study on the reaction H + OH => H O +H by computing quasiclassical trajectories on the same potential-energy surface as recent exact quantum scattering calculations. We calculate reagent state-selected cross-sections and J=0 probabilities, J=0 total cumulative probabilities and thermal rate constants. We performed a rigorous comparison with quantum results, both exact (J=0 probabilities) and approximate (cross-sections and rate constants). Generally, quantum and QCT results agree remarkably well, except for vibrationally excited H , where quantum results show a rich resonance structure. There is very good agreement between QCT and quantum cumulative probabilities above the quantum threshold. However, due to the usual tunnel- ling e?ect the agreement for the rate constants is less good, especially at low temperatures where quantum results are 30-50% above the QCT ones. Finally, by computing J-shifted QCT rate constants, we found that the errors introduced by the J-shifting approximation are of the same order as those introduced by QCT.