Multireference Wavefunction-Based Investigation of the Ground and Excited States of LrF and LrO.

Complete active space self-consistent field (CASSCF) and multireference configuration interaction with Davidson correction (MRCI+Q) calculations have been carried out for lawrencium fluoride (LrF) and lawrencium oxide (LrO) molecules, detailing 19 and 20 electronic states for LrF and LrO, respectively. For LrF, two dissociation channels were considered, Lr( 2 P)+F( 2 P) and Lr( 2 D)+F( 2 P). However, due to the more complex electronic manifold of LrO, three dissociation channels were computed: Lr( 2 P)+O( 3 P), Lr( 2 D)+O( 3 P), and Lr( 2 P)+O( 1 D). In addition, equilibrium bond lengths, harmonic vibrational frequencies ω e , anharmonicity constants ω e χ e , Δ G 1/2 values, and excitation energies T e for the ground and several excited electronic states were calculated for both molecules, for the first time. Bond dissociation energies (BDEs) were calculated for LrF and LrO using several different levels of theory: unrestricted coupled-cluster with single, double, and perturbative triple excitations (UCCSD(T)), density functional theory (B3LYP, TPSS, M06-L, and PBE), and the correlation-consistent composite approach developed for f -elements ( f -ccCA).