Abstract
The group dipole interaction model of the molecular second hyperpolarizability is specialized to describe a molecule composed of interacting isotropic atoms. The model is applied to a set of selected haloalkanes, and using established values for the atom polarizabilities, the atom second hyperpolarizabilities for carbon, hydrogen, fluorine, chlorine, bromine, and iodine are evaluated. The experimental and theoretical molecular second hyperpolarizabilities agree to within an average of 15%.