Structure of the weakly bound triatomic He2Li and He2Na molecules
AbstractWe study the structure of triatomic molecules containing two helium atoms and one alkali-metal atom X (X = Li, Na). The three-body Schrödinger equation is solved in hyperspherical coordinates using the He-He and He-X pair van der Waals potentials available in the literature. We calculate the structural properties of the He2Li and He2Na bound states, and analyze one-dimensional pair and angle distribution functions as well as two-dimensional pair-pair and angle-angle distribution functions. These bound states are characterized by so peculiar weakly bound structures that classifying them into particular sizes and geometrical shapes appears to be elusive. Particularly, the JΠ=0+ excited states of He24Li6 and He24Li7 are found to constitute giant triatomic molecules with their size amounting to several hundred bohrs.