Abstract:
We report a series of quantum-chemical calculations for the ground and some of the low-lying excited states of an isolated LiYb molecule by the spin-orbit multistate complete active space
second-order perturbation theory SO-MS-CASPT2 . Potential energy curves, spectroscopic
constants, and transition dipole moments TDMs at both spin-free and spin-orbit levels are
obtained. Large spin-orbit effects especially in the TDMs of the molecular states dissociating to
Yb 3P0,1,2 excited states are found. To ensure the reliability of our calculations, we test five types
of incremental basis sets and study their effect on the equilibrium distance and dissociation energy
of the ground state. We also compare CASPT2 and CCSD T results for the ground state
spectroscopic constants at the spin-free relativistic level. The discrepancies between the CASPT2
and CCSD T results are only 0.01 Å in equilibrium bond distance Re and 200 cm−1 in
dissociation energy De . Our CASPT2 calculation in the supermolecular state R=100 a.u. with
the largest basis set reproduces experimental atomic excitation energies within 3% error. Transition
dipole moments of the super molecular state R=100 a.u. dissociating to Li 2P excited states are
quite close to experimental atomic TDMs as compared to the Yb 3P and Yb 1P excited states. The
information obtained from this work would be useful for ultracold photoassociation experiments on
LiYb. © 2010 American Institute of Physics. doi:10.1063/1.3475568
