PHYS 34 |
| The title reaction is considered to be the single most important reaction in combustion because of its role in chain branching ignition. The reverse reaction also plays a key role in atmospheric chemistry and interstellar chemistry. As a result, they have attracted much attention in both experiment and theory. Because of the open-shell nature of the species involved, however, experimental measurements are difficult and the results often contain large errors. On the other hand, theoretical studies have so far suffered from the lack of accurate potential energy surfaces and difficulties associated with an accurate quantum treatment of the dynamics. We report our recent work on the quantum dynamic studies of both reactions on an accurate ab initio potential energy surface. The dynamic model includes Coriolis coupling terms that are necessary for an accurate characterization of the reaction dynamics dominated by the floppy HO2 intermediate. The differential and integral cross sections provide convincing evidence that both reactions proceed with a complex-forming mechanism. However, the calculated results also indicate significant non-statistical behaviors. Although showing significant improvement over the previous DMBE potential energy surface, the calculated rate constants on the new ab initio potential energy surface were found to underestimate the experimental data. In addition, the quantum results reveal significant errors in rate constants calculated using the quasi-classical trajectory method and approximate quantum mechanical methods. |
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Electronic Structure and Reaction Dynamics of Open-shell Species
8:00 AM-12:05 PM, Sunday, April 6, 2008 Morial Convention Center -- Rm. 345, Oral
Division of Physical Chemistry |