Global Potential Energy Surface for the H+CH4⇆H2+CH3 Reaction using Neural Networks

A global potential energy surface (PES) for the H+CH4 <-> H-2+CH3 reaction has been constructed using the neural networks method based on 47783 high level ab initio geometry points. Extensive quasi-classical trajectories and quantum scattering calculations were carried out to check the convergence of the PES. This PES, fully converged with respect to the fitting procedure and the number of ab initio points, has a very small fitting error, and is much faster on evaluation than the modified Shepard interpolating PES, representing the best available PES for this benchmark polyatomic system.