Are Roaming and Conventional Saddle Points for H₂CO and CH₃CHO Dissociation to Molecular Products Isolated from Each Other?

High-level ab initio calculations are performed to examine previously unexplored regions of full-dimensional potential energy surfaces that connect the conventional and recently reported “roaming” saddle points for the H 2 CO and CH 3 CHO unimolecular dissociations to form molecular products, H 2 + CO and CH 4 + CO, respectively. The aim of this investigation is to determine whether or not there are large barriers separating these saddle points and their associated intrinsic reaction pathways. The results are of fundamental significance in formulating statistical and reduced dimensionality dynamical approaches to model these reactions, including both pathways.