Accurate ab initio calculation of the Ar-CF4 intermolecular potential energy surface

Ar-CF4 intermolecular interaction potential is studied by ab initio calculations at the MP2 and CCSD(T) levels of theory containing the so-called bond functions ({3s3p2d1f} basis set was chosen) both with and without a correction for the basis-set superposition error. The calculations were performed with Dunning's correlation consistent basis sets (aug-cc-pVXZ, X=D, T, Q, 5) to extrapolate the Ar-CF4 potential energy minimum and intermolecular distance to their complete basis set (CBS) limits. It is shown that the addition of bond functions results in a dramatic improvement in the convergence of the calculated interaction energies at the MP2/aug-cc-pVTZ level. The MP2/{3s3p2d1f}-aug-cc-pVTZ potential energy surface even approaches the CCSD(T)/aug-cc-pVQZ potential energy surface. The potential energy minima and the intermolecular distances are both significantly closer to the CBS limit when using the bond functions, and it implies that adding bond functions in the calculation has a great effect on the interaction energies. We also find that with bond functions included in the CCSD(T)/aug-cc-pVDZ model chemistry, the potential energy minima are extremely close to the CBS limit and are better than the CCSD(T)/aug-cc-pVQZ values. Several levels of theory described in the text were used to determine pairwise analytic potential energy surfaces for Ar+CF4. The analytic potential energy surfaces are in very good agreement with the ab initio values.