Theoretical calculation of a full-dimensional ab initio potential energy surface and prediction of infrared spectra for Xe–CS2

Abstract

An effective four-dimensional (4D) ab initio potential energy surface (PES) for Xe–CS₂ which explicitly involves the intramolecular Q₁ symmetric stretching and Q₃ antisymmetric stretching vibrational coordinates of CS₂ is constructed. The computations are carried out employing single- and double-excitation coupled-cluster theory with a non-iterative perturbation treatment of triple excitations [CCSD(T)] method with a large basis set. Two vibrationally averaged potentials at the ground and ν₁ + ν₃ (ν₁ = 1, ν₃ = 1) excited states are obtained by integrating the 4D potentials over the Q₁ and Q₃ coordinates. The potentials have a T-shaped global minimum and two equivalent linear local minima. The radial discrete variable representation/angular finite basis representation and the Lanczos algorithm are employed to calculate the rovibrational energy levels for Xe–CS₂. The infrared band origin shift associated with the fundamental band of CS₂ is predicted, which is red-shifted by −1.996 cm⁻¹ in the ν₁ + ν₃ region. In addition, we further predict the spectroscopic parameters for the ground and the ν₁ + ν₃ excited states of Xe–CS₂. Compared with the previous Rg–CS₂ (Rg = He, Ne, Ar, Kr) complexes, we found that the complexes of the rare gas atoms with CS₂ display obvious regularities.