A theoretical study of the Renner-Teller effect in the (X)over-tilde2Πg state of C3-

Three-dimensional potential energy functions for the A" and A' components of the (X) over tilde (2)Pi (g) state of C-3(-) have been generated ab initio using the internally contracted multi-reference configuration interaction method. The spin-orbit constant in this state has been calculated from a complete-active-space-self-consistent-field wavefunction. These data were used to solve the linear/linear Renner-Teller problem variationally for J = 1/2, 3/2 and 5/2. Rovibronic levels for K = 0, 1 and 2 were determined for energies up to about 3800 cm(-1). The very large splitting between A" and A' was found to give rise to a strong mixing for the rovibronic Pi and Delta bending states. The results are compared with those obtained experimentally and for similar molecular systems. (C) 2001 Elsevier Science B.V. All rights reserved.