Structure and stability of interstellar molecule C₃S

The singlet and triplet potential energy surfaces of interstellar molecule C₃S are predicted at the UB3LYP/6-311 (d) and UCCSD(T)/6-311 + G(2df) (single-point) levels. The linear singlet isomer CCCS with 1 Σ⁺ electronic state is found to be thermodynamically and kinetically the most stable species on the singlet surface followed by other four singlet isomers, which are unstable on the basis of calculated results. On the triplet surface, the lowest-lying species, which-lies 248.79 kJ/mol above linear singlet species CCCS, is chain CCCS connectivity with ³A′ electronic state. Other four triplet isomers can be considered as unstable species by means of transition state and potential energy surface scan technologies. The structures, vibrational frequencies, dipole moments and rotational constants of an optimized species are also calculated.