Quantum and Classical Studies of the O(3P)+H2(v=0-3,j=0) > OH + H Reaction Using Benchmark Potential Surface
Abstract
We present results of time dependent quantum mechanics (TDQM) and quasi-classical trajectory (QCT) studies of the excitation function for O((3)P) + H2(v=0-3,j=0) - OH + H from threshold to 30 kcal/mol collision energy using benchmark potential energy surfaces Rogers et al. J. Phys. Chem. A 104, 2308 (2000). For H(2)(v=0) there is excellent agreement between quantum and classical results. The TDQM results show that the reactive threshold drops from 10 kcal/mol for v=0 to 6 for v=1, 5 for v=2 and 4 for v=3, suggesting a much slower increase in rate constant with vibrational excitation above v=1 than below. For H(2)(v>0), the classical results are larger than the quantum results by a factor 2 near threshold, but the agreement monotonically improves until they are within approx. 10% near 30 kcal/mol collision energy. We believe these differences arise from stronger vibrational adiabaticity in the quantum dynamics, an effect examined before for this system at lower energies. We have also computed QCT OH(v,'j') state- resolved cross sections and angular distributions. The QCT state-resolved OH(v') cross sections peak at the same vibrational quantum number as the H(2) reagent. The OH rotational distributions are also quite 'hot' and tend to cluster around high rotational quantum numbers. However, the dynamics seem to dictate a cutoff in the energy going into OH rotation. The state-resolved OH distributions were fit to probability functions based on conventional information theory extended to include an 'energy gap' law for product vibrations and angular momentum constraints for product rotations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 16, 2003
- Accession Number
- ADA417669
Entities
People
- B. Maiti
- G. C. Schatz
- M. Braunstein
- S. Adler-golden
Organizations
- Air Force Research Laboratory