Structure and properties of the low-lying electronic states of CeC2 and CeC2+

Theoretical studies on the electronic and thermodynamic properties of several electronic states of CeC2 and CeC2+ have been carried out employing state-of-the-art single- and multireference techniques. The ground and the low-lying electronic states of these two species have been found to possess C-2v triangular structures. A B-3(2) state has been found to be the ground state of CeC2 while for CeC2+ (2)A(2) is the ground state. The computed electron ionization energy is in excellent agreement with experiment. The experimentally observed thermodynamic properties (dissociation and atomization energies) of reactions involving CeC2 dissociation are corrected using the computed gas-phase properties of the molecule and the partition functions. The bent triplet and singlet state of CeC2 exhibit large dipole moments (7.0-10.5 D) and it is consistent with the ionic character (through dative charge transfer) of the cluster in ground and excited states. (C) 2007 American Institute of Physics.