Multi-reference perturbation theory study on the CsYb molecule including the spin-orbit coupling

Abstract

We present CASSCF/XMCQDPT2 level of theory calculations of the ground and sixteen low-lying excited electronic states of the CsYb molecule taking into account the spin-orbit coupling. Spectroscopic constants (electronic term energies, equilibrium internuclear distances, dissociation energies, harmonic vibrational frequencies), transition dipole moments, Franck-Condon factors and vibrational energies of the CsYb molecule have been obtained. The energies of the ground and first exited states at the asymptotic limits definitely satisfy the experimental data for cesium and ytterbium atoms. All the data obtained allow to predict and realize two-photon schemes for producing ultracold CsYb molecules and carry out spectral experiments with them.

Two-photon photoassociation spectroscopy of CsYb: Ground-state interaction potential and interspecies scattering lengths

“…To obtain such a potential, we base the short-range part on electronic structure calculations. Interaction potentials for the 2 Σ ground state of CsYb have been calculated at various levels of electronic structure theory [58,59,94,95]. The potential is dominated by dispersion interactions, with little chemical bonding, due to the large difference in ionisation energies for Cs and Yb [96].…”

“…The well depths D e and equilibrium distances R e for the groundstate potentials from Refs. [94], [58], [59] and [95] are compared with those for our fitted potential in Table III. The minimum of our potential is deeper and at shorter range than any of those from electronic structure calculations, though comparable to those from Refs.…”

Photoassociation of Ultracold CsYb Molecules and Determination of Interspecies Scattering Lengths

“…7.2 using the Leonard-Jones form of the 1 1 Π 1/2 potential given in Ref. [300]. The solutions correspond to various vibrational levels of the molecular potential and are labelled by the vibrational quantum number v, numbered up from zero at the bottom of the potential.…”

“…The molecular curves plotted here are adapted from Ref. [300]. The hyperfine splitting shown on the right is not to scale.…”

Production of ultracold Cs*Yb molecules by photoassociation

“…The electronic state at this threshold is designated 2(1/2) to indicate that it is the second (first excited) state with total electronic angular momentum Ω = 1/2 about the internuclear axis. It correlates at short range with the 1 2 Π 1/2 electronic state in Hund's case (a) notation [52], but at long range the 2 Π 1/2 and 2 Σ 1/2 states are strongly mixed by spin-orbit coupling.…”