DAVID W. SCHWENKE, GALINA M. CHABAN, NASA Ames Research Center, Moffett Field, CA 94035.
We have carried out first principle calculations of electronic transitions in C3. Low lying electronic states have linear or near linear minima, and thus are characterized by D v symmetry labels. The ground state has 1 +g symmetry, and can be resonably treated by triatomic bound state codes that assume the Born-Oppenheimer approximation is valid . The lowest excited state has 1 u symmetry, and explicit coupling between electronic and nuclear angular momentum must be considered: the Renner-Teller effect. We treat this coupling exactly so our results are independent of the choice of coordinates. Furthermore, the 1 u state is perturbed by the lowest triplet state, and we include this coupling as well.