The hydrogen abstraction reaction H + C2H6 → H2(v,j) + C2H5. Part I. A full-dimensional analytical potential energy surface based on ab initio calculations

Using as input data high-level structure electronic calculations, a new full-dimensional analytical potential energy surface (PES), named PES-2018, was developed for the title reaction, which is a valence bond/molecular mechanics based surface that depends on a set of adjustable parameters. The title reaction is practically thermoneutral, -0.18 kcal mol(-1), with a high barrier, 11.62 kcal mol(-1), and it presents features that make it very interesting for kinetics and dynamics studies. The PES simulates the high-level ab initio calculations used in the fitting process, with differences of less than 0.5 kcal mol(-1). The quality of the fitting and the analytical expression was tested by comparing the results from this PES to different ab initio data. In the light of these results we believe that the new PES-2018 surface presents great versatility and satisfactory behaviour for the description of the nine-body reactive system. Based on this PES, in a forthcoming paper (Part II) an exhaustive kinetics and dynamics study of the title reaction will be presented.