Investigations on analytic potential energy function, spectroscopic parameters and vibrational manifolds (J=0) of the SD⁺X³\varSigma^- ion

This paper investigates the spectroscopic properties of the SD^ +(X^3\it\Sigma^ - ) ion by employing the coupled-cluster singles-doubles-approximate-triples CCSD(T) theory combining with the quintuple correlation-consistent basis set augmented with diffuse functions (aug-cc-pV5Z) of Dunning and co-workers. The accurate adiabatic potential energy function is obtained by the least-squares fitting method with the 100 ab initio points, which are calculated at the unrestricted CCSD(T)/aug-cc-pV5Z level of theory over the internuclear separation range from 0.09 to 2.46 nm. Using the potential, it accurately determines the spectroscopic parameters (D_\rm e, \omega _\rm e\chi _\rm e, \alpha _\rm e and B_\rm e). The present D_\rm e, R_\rm e, \omega _\rm e, \omega _\rm e\chi _\rm e, \alpha _\rm e and B_\rm e results are of 3.69119 eV, 0.13644 nm, 1834.949 cm^ - 1, 25.6208 cm^ - 1, 0.1068 cm^ - 1 and 4.7778 cm^ - 1, respectively, which are in remarkably good agreement with the experimental findings. A total of 29 vibrational states has been predicted by numerically solving the radial Schrödinger equation of nuclear motion when the rotational quantum number J equals zero. The complete vibrational levels, classical turning points, inertial rotation and centrifugal distortion constants are reported when J = 0 for the first time, which are in good accord with the measurements wherever available.