A new ab initio potential energy surface and infrared spectra for the Ne–CS2 complex

Abstract

We report a new three-dimensional potential energy surface for Ne–CS2 including the Q3 normal mode for the υ3 antisymmetric stretching vibration of the CS2 molecule. The potential energies were calculated using the supermolecular method at the coupled-cluster singles and doubles level with noniterative inclusion of connected triples [CCSD(T)] with a large basis set containing bond function. Two vibrationally averaged potentials with CS2 at both the ground (υ=0) and the first excited (υ=1)υ3 vibrational states were generated from the integration of the three-dimensional potential over the Q3 coordinate. Each potential was found to have a T-shaped global minimum and two equivalent linear local minima. The radial discrete variable representation (DVR)/angular finite basis representation (FBR) and the Lanczos algorithm were employed to obtain the rovibrational energy levels. The calculated band origin shifts were found to be 0.1812cm−1 and 0.1833cm−1 for 20Ne–CS2 and 22Ne–CS2, respectively, which are all in very good agreement with the experimental values of 0.1804cm−1 and 0.1827cm−1.