Ab initio study of the C2O+ cation

The first electronic states of C2O+ correlating to the first asymptotes of dissociation are presented. From accurate MRCI+Q/cc-pV5Z calculations it is shown that the electronic ground state is the X-2 Pi state and the first excited state the a(4)Sigma(-) state lying very close to the X-2 Pi state, E-eq((4)Sigma(-)) - E-eq((2)Pi) = 2388 cm(-1). For both states the three-dimensional PEFs are determined for displaced geometries in the range -0.35 less than or similar to Delta R-CC less than or similar to+0.6 bohr and -0.29 less than or similar to R-CO less than or similar to+0.3 bohr about the equilibrium bond lengths and 150 degrees <= CCO <= 180 degrees. The rovibronic levels up to 2200cm(-1) and J=P=7/2 are obtained for X-2 Pi and the rovibrational levels of (4)Sigma(-) up to 5000 cm(-1) and K=4. The spin-orbit coupling between both states is investigated.