Electronic spectra of DyF studied by four-component relativistic configuration interaction methods

The electronic states of the DyF molecule below 3.0 eV are studied using 4-component relativistic CI methods. Spinors generated by the average-of-configuration Hartree-Fock method with the Dirac-Coulomb Hamiltonian were used in CI calculations by the KRCI (Kramers-restricted configuration interaction) program. The CI reference space was generated by distributing 11 electrons among the 11 Kramers pairs composed mainly of Dy [4f], [6s], [6p] atomic spinors, and double excitations are allowed from this space to the virtual molecular spinors. The CI calculations indicate that the ground state has the dominant configuration (4f⁹)(6s²)(Ω = 7.5). Above this ground state, 4 low-lying excited states (Ω = 8.5, 7.5, 7.5, 7.5) are found with dominant configurations (4f¹⁰)(6s). These results are consistent with the experimental studies of McCarthy et al. Above these 5 states, 2 states were observed at T₀ = 2.39 eV, 2.52 eV by McCarthy et al. and were named as [19.3]8.5 and [20.3]8.5. McCarthy et al. proposed that both states have dominant configurations (4f⁹)(6s)(6p), but these configurations are not consistent with the large R_e’s (∼3.9 a.u.) estimated from the observed rotational constants. The present CI calculations provide near-degenerate states of (4f¹⁰)(6p_3/2,1/2), (4f¹⁰)(6p_3/2,3/2), and (4f⁹)(6s)(6p_3/2,1/2) at around 3 eV. The former two states have larger R_e (3.88 a.u.) than the third, so that it is reasonable to assign (4f¹⁰)(6p_3/2,1/2) to [19.3]8.5 and (4f¹⁰)(6p_3/2,3/2) to [20.3]8.5