Dynamics of the He+He₂⁺（v=0） Exchange Reaction on a New Potential Energy Surface for Ground-State He₃⁺

A many-body expansion analytical function has been derived by fitting to CI results calculated by Ackermann et al（Mol. Phys. 68, 279（1989））. The optimum function gives a standard deviation to data points of 0.05 eV. The surface as a triangular graph shows a linear symmetrical minimum with a distance of R_e=2.3251 Bohr as well as a T-shaped metasta-ble molecule, which are in good agreement with the CI study. According to this function, a quasiclassical trajectory study of the thermoneutral helium exchange reaction was made. Reactive cross sections have been obtained at 220,270 and 320K. From the 320K results a rate constant has been obtained of 4.26×10¹³cm³∙s^-1∙mole^-1.