Theoretical spin-orbit calculations of low-lying electronic states of cerium monoxide

Abstract The 69 Ω lowest lying electronic states of CeO molecules have been investigated by employing MRCI and CASPT2 ab initio methods and by including the Spin Orbit Coupling (SOC). The potential energy curves (PECs) of all the lowest singlet and triplet Λ−S states below 22,850 cm−1 have been constructed and considered to calculate the related spectroscopic properties. The obtained results of Λ-S states and their corresponding Ω components have been successfully compared to the available experimental parameters. Based on these results, the component 3Φ2 (Ω=2) of the ground state X3Φ has been assigned as the lowest substate of CeO. 23 unobserved components have been predicted for the first time and new assignments have been given for many observed states. Dipole-allowed transition moments between the predicted electronic states have been reported. Vibrational levels up to v = 5 for the first seven lowest components (1)(Ω=2), (1) (Ω=3), (1) (Ω=1), (2)(Ω=2) (1)(Ω=0−), (2)(Ω=1) and (1)(Ω=0+) have been obtained by solving the radial Schrodinger equation to study the possible perturbations between these levels.