Ab initio potentials for weakly interacting systems: Homonuclear rare gas dimers

Abstract

AbstractA series of high‐level ab initio interatomic potentials for the homonuclear rare gas dimers He2, Ne2, and Ar2 is presented, with predictions of rovibrational spectroscopic parameters and second virial coefficients. These potentials were created by using d‐aug‐cc‐pVnZ, n = D,T,Q basis sets, MP4 and CCSD(T) correlation energy treatments, the counterpoise correction to the basis set superposition error, and extrapolation schemes for estimating complete basis set (CBS) limits. A careful FCI correction was added to our best He2 CCSD(T) potential. The characteristic parameters De, Re, k, and σ of the ab initio potentials were compared with those of reliable empirical and ab initio potentials. Our best results for He2 recovered 99.9% of Janzen's SAPT2 well depth Janzen, A.R.; Aziz, R.A. J Chem Phys 1997, 107, 914–919. In the case of Ar2, we recovered 99.8% of Aziz's HFDID1 well depth Aziz, R.A. J Chem Phys 1993, 99, 4518–4525. For neon, second virial coefficients typically came to within 0.5–1.0 cm3mol−1 of experimental values and rovibrational energy levels exhibited errors of about 1.4 cm−1. Our best argon results exhibited second virial coefficients in agreement of 0.25 cm3mol−1 with experiment and rovibrational energy level errors around 0.2 cm−1. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 95: 303–312, 2003