Quantum and Quasi-Classical Studies of the O(3P) + HCl yields OH + Cl(2P) Reaction Using Benchmark Potential Surfaces (PREPRINT)
Abstract
We have performed quantum mechanical (QM) dynamics calculations within the independent-state approximation with new benchmark triplet A" and A' surfaces [B. Ramachandran et al. J. Chem. Phys. 119, 9590 (2003).] for the ro-vibronic state-to-state measurements of the reaction O(3P) + HCl(v=2,j=1,6,9)  OH(v j ) + Cl(2P) [Zhang et al. J. Chem. Phys. 94, 2704 (1991)]. The QM and experimental rotational distributions peak at similar OH(j ) levels, but the QM distributions are significantly narrower than the measurements and previous quasi-classical dynamics studies. The OH(low j ) populations observed in the measurements are nearly absent in the QM results. We have also performed quasi-classical trajectory with histogram binning (QCT-HB) calculations on these same benchmark surfaces. The QCT-HB rotational distributions, which are qualitatively consistent with measurements and classical dynamics studies using other surfaces, are much broader than the QM results. Application of a Gaussian binning correction (QCT-GB) dramatically narrows and shifts the QCT-HB rotational distributions to be in very good agreement with the QM results. The large QCT-GB correction stems from the special shape of the joint distribution of the classical rotational/vibrational action of OH products. We have also performed QM and QCT calculations for the transition, O + HCl(v=0,T=300 K)  OH(v j ) + Cl from threshold to ~130 kcal mol-1 collision energy as a guide for possible future hyperthermal O-atom measurements. We find in general a mixed energy release into translation and rotation consistent with a late barrier to reaction. Angular distributions at high collision energy are forward peaked, consistent with a stripping mechanism. Direct collisional excitation channel cross sections, O + HCl(v=0,T=300)  O + HCl(v =1), in the same energy range are large, comparable in
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 25, 2004
- Accession Number
- ADA445201
Entities
People
- B. Ramachandran
- J. W. Duff
- Joel Bowman
- M. Braunstein
- Tiao Xie
Organizations
- Emory University