Ab initio characterization of the Ne-I2 van der Waals complex: intermolecular potentials and vibrational bound states.

A theoretical study of the potential energy surface and bound states is performed for the ground state of the NeI(2) van der Waals (vdW) complex. The three-dimensional interaction energies are obtained from ab initio coupled-cluster, coupled-cluster single double (triple)/complete basis set, calculations using large basis sets, of quadruple- through quintuple-zeta quality, in conjunction with relativistic effective core potentials for the heavy iodine atoms. For the analytical representation of the surface two different schemes, based on fitting and interpolation surface generation techniques, are employed. The surface shows a double-minimum topology for linear and T-shaped configurations. Full variational quantum mechanical calculations are carried out using the model surfaces, and the vibrationally averaged structures and energetics for the NeI(2) isomers are determined. The accuracy of the potential energy surfaces is validated by a comparison between the present results and the corresponding experimental data available. In lieu of more experimental measurements, we also report our results/predictions on higher bound vibrational vdW levels, and the influence of the employed surface on them is discussed.