Natural orbital functional description of van der Waals interactions: A case study of the effect of the basis set for the helium dimer

We report on natural orbital functional calculations of the potential energy curve of the helium dimer. The performance of the recently proposed natural orbital functional (Piris et al. J Chem Phys 2007, 126, 214103) for the treatment of van der Waals interactions is assessed with respect to the increase of the number functions of the augmented correlation consistent polarized valence basis set series. Satisfactory converged towards the experimental equilibrium distance and binding energy is observed with the increase of the number of functions of the basis set. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008