SIMBAD references

Recently, we reported ab initio quartic force fields (QFFs) for the cyclic and linear forms of the C₃H₃⁺ molecular cation, referred to as c-C₃H₃⁺ and l-C₃H₃⁺. These were computed using high levels of theory. Specifically the singles and doubles coupled-cluster method that includes a perturbational estimate of connected triple excitations, CCSD(T), was used in conjunction with extrapolation to the one-particle basis set limit, and corrections for scalar relativity and core correlation were included. In the present study, we use these QFFs to compute highly accurate fundamental vibrational frequencies and other spectroscopic constants for the c-¹³CC₂H₃ ⁺, c-C₃H₂D⁺, c-¹³CC₂H₂D⁺ isotoplogues of c-C₃H₃⁺, and the H₂CCCD⁺, HDCCCH⁺, H₂¹³CCCH⁺, H₂C¹³CCH⁺, and H₂CC¹³CH⁺ isotopologues of l-C₃H₃⁺. Improvements in ab intitio methods have now made it possible to identify small molecules in an astronomical observation without the aid of high-resolution experimental data. We also report dipole moment values and show that the above-mentioned cyclic isotopologues have values of 0.094, 0.225, and 0.312 D, respectively, while the l-C₃H₃⁺ isotopologues have values that range between 0.325 and 0.811 D. Thus, it is hoped that the highly accurate spectroscopic constants and data provided herein for the ¹³C and deuterium isotopologues of the cyclic and linear forms of C₃H₃⁺ will enable their identification in astronomical observations from the Herschel Space Observatory, the Stratospheric Observatory for Infrared Astronomy, the Atacama Large Millimeter Array, and in the future, the James Webb Space Telescope.