Axilrod-Teller interaction

The Axilrod-Teller interaction for three-body interactions is given by (Ref. 1):

$\Phi _{123}=C{\frac {3\cos(\gamma _{1})\cos(\gamma _{2})\cos(\gamma _{3})+1}{r_{12}^{3}r_{23}^{3}r_{31}^{3}}}$

where $r_{ij}$ are the lengths of the sides and $\gamma _{i}$ are the angles of the triangle formed by the three atoms.

References

1. B. M. Axilrod and E. Teller "Interaction of the van der Waals Type Between Three Atoms", Journal of Chemical Physics 11 pp. 299-300 (1943)