The vibrational dependence of an interaction potential for a bending mode: NH3–He and the inversion motion

The electron gas interaction potential for the NH3–He system was calculated for five different NH3 C3v geometries. These geometries were chosen to lie along a one-dimensional minimum energy pathway for inversion, as parametrized by the Hartree–Fock calculations of Stevens. The inversion dependence of the interaction potential is well described by a second-order polynomial fit to the spherical harmonic expansion coefficients. The interaction potential was averaged over the vibrational motion in the ground state inversion doublets. The inversion motion is found to have a negligible effect on the ’’rigid-top’’ interaction potential.