Line Lists for the State of CS

Abstract

Rotation-vibrational line lists for eight isotopologues of carbon monosulphide (CS; 12C32S, 12C33S, 12C34S, 12C36S,13C32S, 13C33S,13C34S, and 13C36S) in their ground electronic state (X1Σ+) are calculated. An empirical potential function with the corrections of Born–Oppenheimer breakdown effects, which are determined by a direct potential fitting approach using over 4300 observed transition frequencies of 12C32S, 12C33S, 12C34S, and 13C32S, is used in line list calculations. The reproduced transition frequencies are within the observation uncertainties for the isotopologues with experimental data. The dipole moment functions are calculated using an ab initio method at a multireference configuration interaction method/cc-pv5z level with a large active space of electronic configuration. The dipole moment at equilibrium nuclear separation is almost identical to the experimental result. The calculated intensities agree excellently with the laboratory observations at 2573 K. The corresponding Einstein A coefficients and oscillator strengths are predicted. Partition functions for temperatures up to 7500 K have been calculated. The line lists can be used for spectroscopic measurements of CS in astronomical environments of various temperatures.