Exchange-hole dipole moment and the dispersion interaction: high-order dispersion coefficients

In recent publications [A. D. Becke and E. R. Johnson, J. Chem. Phys. 122, 154104 (2005); E. R. Johnson and A. D. Becke 123, 024101 (2005)] we have demonstrated that the position-dependent dipole moment of the exchange hole can be used to generate dispersion interactions between closed-shell systems. Remarkably accurate C6 coefficients and intermolecular potential-energy surfaces can be obtained from Hartree-Fock occupied orbitals and polarizability data alone. In the present work, our model is extended to predict C8 and C10 coefficients as well. These higher-order coefficients are obtained as easily as C6 and with comparable accuracy.