Theoretical calculation of a full-dimensional ab initio potential energy surface and prediction of infrared spectra for Xe–CS(2)

An effective four-dimensional (4D) ab initio potential energy surface (PES) for Xe–CS(2) which explicitly involves the intramolecular Q(1) symmetric stretching and Q(3) antisymmetric stretching vibrational coordinates of CS(2) 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 ν(1) + ν(3) (ν(1) = 1, ν(3) = 1) excited states are obtained by integrating the 4D potentials over the Q(1) and Q(3) 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–CS(2). The infrared band origin shift associated with the fundamental band of CS(2) is predicted, which is red-shifted by −1.996 cm(−1) in the ν(1) + ν(3) region. In addition, we further predict the spectroscopic parameters for the ground and the ν(1) + ν(3) excited states of Xe–CS(2). Compared with the previous Rg–CS(2) (Rg = He, Ne, Ar, Kr) complexes, we found that the complexes of the rare gas atoms with CS(2) display obvious regularities.