A London-type formula for the dispersion interactions of endohedral A@B systems
A London-type formula is derived for endohedral systems. It involves the static dipole polarisability, α1(A) of the inner system, A, and a new type of dipole polarisability, α−2(B) with an r−2 radial operator, for the outer system, B. The new formula has no explicit dependence on the radius, R, of B. The predicted interaction energies are compared against MP2 supermolecular calculations for A@C60, A = He–Xe, Zn, Cd, Hg, and CH4.