Coupled cluster calculations for three low-lying doublet states of linear C10− Original Research Article

Making use of a large basis set of 270 contracted Gaussian-type orbitals partially restricted coupled-cluster calculations including connected triple substitutions (RCCSD(T)) have been carried out for the ground state X̃ 2Πu and two low-lying excited doublet states (2Σg+ and 2Πg) of linear C10−. The calculated Te value for the 2Πg state amounts to 10 890 cm−1, in close agreement with the To value of 10 338 cm−1 obtained by absorption spectroscopy in a neon matrix. The observed peaks at 12 330 and 12 430 cm−1 are assigned to the 201 and 101 transitions. For the 2Σg+ state, we predict a Te value of 9 951 cm−1. Besides the adiabatic peak, the 201 transition shows up strongest in the 2Σg+←X̃ 2Πu band.