A dynamic reaction coordinate approach to ab initio reaction pathways: Application to the 1,5 hexadiene Cope rearrangement

A modified dynamic reaction coordinate algorithm for tracing reaction paths is implemented in the framework of ab initio molecular orbital calculations. This method requires fewer energy and gradient evaluations than the traditional intrinsic reaction coordinate methodology and produces reaction pathways of acceptable accuracy. The approach is applied to the 1,5 hexadiene Cope rearrangement for which we trace the pathways passing through the chair and boat transition states. Analysis of the lowest energy pathway indicates that the rearrangement is concerted and synchronous.