ON THE ANISOTROPY OF THE TRIPLE-DIPOLE DISPERSION ENERGY FOR INTERACTIONS INVOLVING LINEAR-MOLECULES

A computationally convenient expression for the exact anisotropic trip le-dipole (DDD) dispersion energy for interactions involving linear (S igma state) molecules is developed. The input data required for its ev aluation are the isotropic and anisotropic dipole oscillator strengths , and excitation energies, for the interacting species. The anisotropy of the DDD energy for three-body molecular systems is investigated, r elative to that from a frequently used average energy expression for D DD, using interactions involving H-2, Ne and N-2 as examples.