Computational investigation by ab initio methods of the spectroscopic characteristics of hafnium monosulfide.

The lowest-lying electronic states of 180Hf32S molecule have been described by using the theoretical ab initio methods, state-averaged full valence complete active space self-consistent field (SA-CASSCF) and multireference configuration interaction with single and double excitation (MRCI-SD). These calculations have predicted 22 electronic states below 40,124 cm-1. The unobserved states [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] have been explored for the first time. The potential energy curves (PECs) have been constructed, and the term energy values at equilibrium Te, vibrational constants ωe, and ωeχe have been calculated for all predicted states. Also, the permanent dipole moments (PDMs) as well as the transition dipole moments (TDMs) have been examined and presented as function of the internuclear distance R. In addition, by employing the spin-orbit coupling in the calculations, 43 Ω± components have been obtained below 40,645 cm-1. The observed states, named A1Σ+ and B1Π, have been assigned respectively as [Formula: see text] and [Formula: see text] of [Formula: see text]. All the calculated spectroscopic constants are found in good agreement with the experiment.

Theoretical study of the electronic structure of mono-bromide of lanthanum molecule including spin-orbit coupling effects.

Among the family of lanthanide halides compounds, this work is devoted to the third halogen bromine. The presented lanthanum bromide LaBr molecule has a remarkable scientific interest regarding the other molecules because it presents few experimental studies and only one theoretical study. The theoretical electronic structure of the LaBr molecule is achieved by using the post-Hartree-Fock methods manifested by the complete active space self consistent field (CAS-SCF) method and the multi reference configuration interaction with single and double excitation (MRCI-SD) method. All of these calculations are performed via the quantum chemistry software MOLPRO. We predicted for the first time in the literature, 24 lowest-lying electronic states in the representation 2S+ 1Λ(±) and their corresponding components in the representation Ω(±) when taking into account the spin-orbit coupling (SOC), situated below 22,000 cm- 1. We calculated the spectroscopic constants for both cases (without/with SOC effects) related to the 13 singlet and 11 triplet states and for their components. We drew also in this paper the potential energy curves (PECs in a range of internuclear distance R varying from 2.00 to 4.22 Å. Graphical AbstractPotential energy curves for 13 singlet electronic states of LaBr.