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

We report a new three-dimensional potential energy surface for Ne–CS2 including the Q3 normal mode for the υ 3 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 ) υ 3 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 0.1812 cm−1 and 0.1833 cm−1 for 20Ne–CS2 and 22Ne–CS2, respectively, which are all in very good agreement with the experimental values of 0.1804 cm−1 and 0.1827 cm−1.