First principles investigation of the electronic structure of the iron carbide cation, FeC+

We have studied 40 states of the diatomic iron carbide cation FeC+ by multireference methods coupled with relatively large basis sets. For most of the states, we have constructed complete potential energy curves, reporting dissociation energies, usual spectroscopic parameters, and bonding mechanisms for the lowest of the studied states. The ground state is of (2)Delta symmetry, with the first excited state (a(4)Sigma(-)) lying 18 kcal/mol higher. The X-2 Delta state displays a triple-bond character, with an estimated D-0 value of 104 kcal/mol with respect to the adiabatic products or 87 kcal/mol with respect to the ground-state fragments.