Quantum transition state dynamics of the cyclooctatetraene unimolecular reaction on ab initio potential energy surfaces

- Calculation of transition-state spectrum of cyclooctatetraene unimolecular reaction.
- Three degree-of-freedom reduced-dimensionality quantum dynamics model is used.
- Reduced-dimensionality model that can describe ring-inversion and bond-alternation.
- Construction of ab initio CASSCF-level potential energy surfaces.

The cyclooctatetraene (COT) anion has a stable D4h structure that is similar to the transition state configurations of the neutral C-C bond-alternation (D4h ↔ D8h ↔ D4h) and ring-inversion (D2d ↔ D4h ↔ D2d) unimolecular reactions. The previously measured photodetachment spectrum of COT− revealed the reaction dynamics in the vicinity of the two transition states on the neutral potential energy surface. In this work, the photodetachment spectrum is calculated quantum mechanically on ab initio-level potential energy surfaces within a three degree-of-freedom reduced-dimensionality model. Very good agreement has been obtained between theory and experiment, providing reliable interpretations for the experimental spectrum. A detailed picture of the reactive molecular dynamics of the COT unimolecular reaction in the transition state region is also discussed.

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