The noble gas dimers as a probe of the energetic contributions of dispersion and short-range electron correlation in weakly bound systems

The binding of the noble gas dimers is examined using a theory in which the Hartree-Fock interaction energy is augmented with both a short-range correlation term derived from the theory of a uniform electron-gas plus a dispersion energy damped according to the theory of Jabobi and Csanak. The good agreement between the predicted and experimental binding energies and equilibrium inter-nuclear separations confirms that this approach captures the essential physics of the interaction. A review of other methods confirms the previously reported failures of density functional theory. A further survey shows that fully ab initio variational methods must be taken to the very refined level of coupled cluster theory with a large quadruple or quintuple zeta basis set if they are to achieve greater accuracy than the approach presented here.