The effect of κ-regularization (see Eq. 8) on interaction energies is given in Table for the NeAr system considered in Figs. : Interaction energies (kcal/mol) calculated as the sum of Hartree-Fock interaction energies and respective κMP2 correlation interaction energies. κ → ∞ corresponds to the results without regularization. The spin-resolved numbers are obtained considering only the opposite-spin (os) or same-spin (ss) part of κMP2. Additional interaction energies for comparison: E CCSD(T) = -0.08294 and E HF = 0.08543.