Ab initio Intermolecular Potential Energy Surface and Calculation of Second Virial Coefficients for the Cl2–Cl2 Dimer

Abstract

The results presented in this paper are the ab initio intermolecular potentials and the second virial coefficient, B 2 ( T ) of the dimer Cl 2 -Cl 2 . These ab initio potentials were proposed by the quantum chemical calculations at high level of theory CCSD (T) with basis sets of Dunning’s valence correlation-consistent aug-cc-pV m Z ( m = 2, 3); these results were extrapolated to complete basis set limit aug-cc-pV23Z. The ab initio energies of complete basis set limit aug-cc-pV23Z resulted from the exponential extrapolation were used to construct the 5-site pair potential functions. The second virial coefficients for this dimer were predicted from those with four-dimensional integration. The second virial coefficients were also corrected to first-order quantum effects. The results turn out to be in good agreement with experimental data, if available, or with those from empirical correlation. The quality of ab initio 5-site potentials proved the reliability for prediction of molecular thermodynamic properties.