Investigations on analytic potential energy function, spectroscopic parameters and vibrational manifolds (J = 0) of the SD+ (X3Σ−) ion

This paper investigates the spectroscopic properties of the SD+ (X3Σ−) 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 (De, ωeχe, αe and Be). The present De, Re, ωe, ωeχe, αe and Be results are of 3.69119eV, 0.13644nm, 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. (atomic and molecular physics)