Ab initio properties of Li-group-II molecules for ultracold matter studies

Abstract

We perform a systematic investigation of the electronic properties of the 2 Σ + ground state of Lialkaline-earth dimers. These molecules are proposed as possible candidates for quantum simulation of lattice-spin models. We apply powerful quantum chemistry coupled-cluster method and large basis sets to calculate potential energies and permanent dipole moments for the LiBe, LiMg, LiCa, LiSr, and LiYb molecules. Agreement of calculated molecular constants with existing experimental data is better than or equal to 8%. Our results reveal a surprising irregularity in the dissociation energy and bond length with an increase in the reduced mass of the molecule. At the same time the permanent dipole moment at the equilibrium separation has the smallest value between 0.01 a.u. and 0.1 a.u. for the heaviest (LiSr and LiYb) molecules and increases to 1.4 a.u. for the lightest (LiBe), where 1 a.u. is one atomic unit of dipole moment. We consider our study of the 2 Σ + molecules a first step towards a comprehensive analysis of their interactions in an optical trap.

Ultracold chemistry with alkali-metal–rare-earth molecules

“…[20] showed that the ground-state contribution dominates for a heavy v = 0, j = 0 RbCs molecule and is small but nonnegligible for the lighter KRb. The LiYb molecule has a very small permanent dipole moment of 0.011ea 0 [45] at equilibrium separation R e = 6.71a 0 and transitions to the electronically excited states dominate. Here, e is the charge of the electron.…”

“…In this paper we use the spectroscopicallyaccurate X 1 Σ + g potential for Li 2 [44] and our previously determined ab initio X 2 Σ + potential for LiYb [45]. Both pair-wise potentials were expanded to large internuclear separation using the best-known van der Waals coefficients [50,51].…”

“…Earlier studies for the quartet potential of homonuclear and heteronuclear alkali-metal trimers [41][42][43] showed that non-additive effects are significant. An improved trimer potential is then created by adding the accurate experimental Li 2 ground state potential [44] and an ab initio theoretical LiYb potential determined with a larger basis set [45] to the three-body potential. No spectroscopic measurement of the LiYb potential exists at this time.…”

Photoassociative production of ultracold heteronuclearYbLi*molecules

“…The ground Yb( 1 S 0 )+Li( 2 S 1/2 ) state potential was calculated in one of our earlier papers [26] using a nonrelativistic coupled cluster method. We presented its long-range van der Waals coefficient separately in [13].…”

Long-range and frustrated spin-spin interactions in crystals of cold polar molecules

“…1 (b). In the following we illustrate a basic encoding scheme for the case of a molecule with a 2 Σ ground state [54], where states |g and |e are represented in two Zeeman sublevels of two excited rotational states. However, we point out that recently several other schemes for tunable dipoledipole interactions for spin and/or rotational degrees of freedom [37,42,43] have been suggested which could also be adapted for the present purpose.…”