Ab initio potential energy surface and predicted microwave spectra for ArOCS dimer and structures of Ar_nOCS (n = 2–14) clusters

Abstract

An ab initio potential energy surface for the Ar--OCS dimer was calculated using the coupled-cluster singles and doubles with noniterative inclusion of connected triples [CCSD(T)] with a large basis set containing bond functions. The interaction energies were obtained by the supermolecular approach with the full counterpoise correction for the basis set superposition error. The CCSD(T) potential was found to have two minima corresponding to the T-shaped and the collinear Ar--SCO structures. The two-dimensional discrete variable representation method was employed to calculate the rovibrational energy levels for five isotopomers Ar--OCS, Ar--OC34S, Ar--O13CS, Ar--18OCS, and Ar--17OCS. The calculated pure rotational transition frequencies for the vibrational ground state of the five isotopomers are in good agreement with the observed values. The corresponding microwave spectra show that the b-type transitions (Delta Ka = +/-1) are significantly stronger than the a-type transitions (Delta Ka = 0). Minimum-energy structures of the Ar2--OCS trimer were been determined with MP2 optimization, whereas the minimum-energy structures of the Arn--OCS clusters with n = 3-14 were obtained with the pairwise additive potentials. It was found that there are two minima corresponding to one distorted tetrahedral structure and one planar structure for the ternary complex. The 14 nearest neighbor Ar atoms form the first solvation shell around the OCS molecule.

Rotational spectra of the van der Waals complexes of molecular hydrogen and OCS

“…In deciding which combination to use we are aided once again by previous ab initio calculations on atom-OCS complexes, in which ͗R͘, ͗͘, and calculated rotational constants are presented. 30,39,40 Examining HeOCS, NeOCS, and ArOCS shows that R values determined using A , C or B , C are within ϳ0.01 Å of ͗R͘, while taking the average of the three values gives the best estimate of ͗͘, lying within 0.1°for NeOCS and ArOCS and within 0.5°for HeOCS. Thus, we use A , C or B , C to determine R, and the average from the three combinations to determine .…”

Theoretical prediction of the linear isomers for rare gas-carbon disulfide complexes: He-CS2, Ne-CS2, and Ar-CS2

“…4 Species such as CO 2 , OCS, N 2 O, and CS 2 belong to a class and have similar properties, due to their isovalent electrons. Except for Rg-CS 2 (Rg = He, Ne, Ar, Kr, and Xe) complexes, the complexes consisting of such species (CO 2 , a) Electronic addresses: zhenglimin@wipm.ac.cn; cxduan@phy.ccnu.edu.cn; yplu@ntu.edu.sg OCS, N 2 O) and rare gas atoms have received much attention in both experimental [5][6][7][8][9][10][11][12] and theoretical studies, [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] due to their fundamental nature and practical importance. In experiment, the microwave and infrared spectra for these complexes were reported widely [8][9][10][11][12] and showed that each complex has a T-shaped structure.…”

“…In theoretical calculations, many ab initio potential energy surfaces for these complexes have been available in literatures. [16][17][18][19][20][21][22][23][24][25][26][27][28][29] Very similar features are found on their PESs, such as the global "T-shaped" minimum, local linear minima, and saddle points. The intermolecular interactions in these complexes vary systematically with both the polarizability of the rare gas atoms and with the electronic structures of the linear molecules.…”

Ab initiointermolecular potential energy surfaces for the Ar–NCCN van der Waals complexes

“…Because of symmetry given by Equation (12), only even values of n and l are acceptable physically in the long-range part of potential energy and in this work, X = cos 2 (θ ) is used in the short-range part of potential energy surface in this work although, in other works [8,14,16] X = cos (θ ) is used.…”