Coupled cluster calculations for three low-lying doublet states of linear C10-

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 (X) over tilde(2) Pi(u) and two low-lying excited doublet states ((2) Sigma(g)(+) and (2) Pi(g)) of linear C-10(-). The calculated T-e value fcr the (2) Pi(g) state amounts to 10 890 cm(-1), in close agreement with the T-0 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 2(0)(1) and 1(0)(1) transitions. For the 2 Sigma(g)(+) state, we predict a T-e value of 9951 cm(-1). Besides the adiabatic peak, the 2(0)(1) transition shows up strongest in the (2) Sigma(g)(+) <-- (X) over tilde(2) Pi(u) band. (C) 1997 Elsevier Science B.V.