Potential for the Interaction of Atoms and Heavy Polar Molecules in Thermal Scattering

The anisotropy of a molecule interacting with an atom in thermal collisions is given a more fundamental basis by separating the effects of the motion of the electrons through mutual induction and through the rotation of the nuclei to which they are connected. For heavy polar molecules with an asymmetric mass distribution the positions of the centers of dispersive and electrostatic interaction on the internuclear axis are different from the center of mass. Most of the anisotropy is accounted for by the dynamical effect of these displacements. Two models are proposed which are applicable in classical mechanics. The total scattering cross sections have been evaluated for the partners TIF and Ar. The anisotropy parameter thus derived is in agreement with experiment.