Contribution of Octopole—Octopole Interactions to the Excess Properties of Mixtures of Tetrahedral Molecules

The contribution to thermodynamic properties of the interaction between bond dipoles of adjacent tetrahedral molecules (such as CF4) has been estimated by calculating the octopole—octopole effect (a) between molecules in an isolated pair and (b) in a rigid lattice. The effect is small and cannot account, at best, for more than a small part of the anomalous excess free energies of systems such as CF4+CH4.