Knowledge Bank

The bound long-range $Cs20g-$ state dissociating into $Cs(6s2S1/2)+Cs(6p2P3/2)$ and correlated at smaller distances to the slightly bound (1)$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}\Pi g$ state was predicted in 1985 [1] to have a well depth of $\sim 76cm-1$ at an equilibrium internuclear separation of $\sim 26a0$. In this previous work, we approximated the interaction energy via the usual multipolar expansion up to $R-8$ and we neglected both exchange and overlap effects. Considering the LeRoy [2] or modified LeRoy criteria [3], it appears that such approximations can be considered as valid for $RL>26a0$ or $RML>23a0$. Then inner turning points of the potential are at internuclear separations for which exchange and overlap effects have to be considered. Here we have improved our description of the potential including these two contributions and using more accurate values for the expansion coefficients $Cn$. We have also extended our work to the predictions of the hyperfine structure of the $Cs20g-$ state by considering basis functions describing atomic hyperfine structure.