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

摘要

An effective four-dimensional (4D) ab initio potential energy surface (PES) for Xe-CS2 which explicitly involves the intramolecular Q(1) symmetric stretching and Q(3) 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 nu(1) + nu(3) (nu(1) = 1, nu(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-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 nu(1) + nu(3) region. In addition, we further predict the spectroscopic parameters for the ground and the nu(1) + nu(3) 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.