An ab initio, analytically fitted, global potential energy surface for the ground electronic state of He₃⁺

A high quality, global potential energy surface (PES) which can be used for detailed quantum dynamical studies is required to definitively address questions of the relative importance of the one-step vs the two-step formation mechanism and the role of symmetry in the observed kinetic isotope effects for this deceptively simple appearing reaction. The first step toward the objective with the development of an analytical global PES that adiabatically describes the ground electronic state is presented.