A new ab initio potential energy surface and microwave and infrared spectra for the Ne–CO2 complex

We report a new three-dimensional potential energy surface for Ne-CO(2) including the Q(3) normal mode for the υ(3) antisymmetric stretching vibration of the CO(2) 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)], using a large basis set supplemented with midpoint bond functions. Two vibrationally averaged potentials with CO(2) at both the ground (υ=0) and the first (υ=1) vibrational υ(3) excited states were generated from the integration of the three-dimensional potential over the Q(3) coordinate. Each potential was found to have a T-shaped global minimum and two equivalent linear local minima. The radial DVR/angular FBR method and the Lanczos algorithm are applied to calculate the rovibrational energy levels. Comparison with the available observed values showed an overall excellent agreement for the microwave and infrared spectra. The calculated band origin shifts were found to be 0.1306 and 0.1419 cm(-1) for Ne-CO(2) and Ne-C(18)O(2), respectively, which are very close to the experimental values of 0.1303 and 0.1432 cm(-1).