A theoretical investigation on the HCCS radical and its ions

The thioketenyl (HCCS) radical and its related cation, HCCS+, and anion, HCCS-, have been investigated at a high level of accuracy. The singles and doubles coupled-cluster method including a perturbational correction for connected triple excitations, CCSD(T), in conjunction with correlation consistent basis sets ranging in size from quadruple to sextuple zeta have been employed. Extrapolation to the complete basis set limit has been used with accurate treatments of core-valence correlation effects to accurately predict equilibrium structures, dipole moments as well as ionization potential and electron affinity. For all the species studied, harmonic vibrational frequencies have also been evaluated to obtain zero-point corrections to energies