Revisiting roaming trajectories in ketene isomerization at higher dimensionality

Abstract

Roaming dynamics have been observed in a threedimensional model of the ketene isomerization reaction. The roaming trajectories sample the region between the outer potential barriers closest to the respective ketene isomers and involve turning points along the reaction coordinate in a polar representation. These roaming trajectories avoid the intrinsic reaction coordinate and the intermediates to which it is associated. Thus, one-dimensional transition state theory ( TST ) is generally insuffi cient as has been confi rmed through an analysis of the reactive fl ux along the dividing surface ( DS ). A global representation of the DS , however, leads to accurate TST rate constants. The exact and TST microcanonical rates of isomerization have been obtained for the three-dimensional model and compare well to experiment. The global DS is therefore particularly important for obtaining rates in reactions that exhibit roaming. This work thus confi rms the fi ndings of our previous two-dimensional treatment of ketene isomerization ( Ulusoy et al. in J. Phys. Chem. A 117:7553–7560, 2013).