Axilrod-Teller interaction
From SklogWiki
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.