An analytic function for the three-body potential of He3

An accurate representation of the three-body potential for the ground state of neutral He3 has been obtained by fitting to high quality ab initio data. The calculations show that the 3rd order, triple-dipole dispersion energy is of minimal importance in comparison with the three-body exchange term except at very large internuclear separations. Damping of the triple-dipole term is better described by a product of damping functions in each of the three internuclear distances than by a single damping function with the perimeter of the triangle as a variable.