On the stabilization of the Li$$^+$$-Li$$^+$$ interaction by microsolvation with rare-gas atoms

Intuitive arguments lead us to expect that ionic species of like charge will be destabilized by repulsion. Nonetheless, it is possible to mitigate such repulsion by involving other type of interactions so that a stable or, at least, a metastable structure can be formed. In this work, we study the stabilization of the Li $$^+$$ -Li $$^+$$ interaction by the step-wise addition of either argon or krypton atoms. The critical size for the formation of metastable (Li $$^+$$ -Li $$^+$$ )Ar $$_n$$ and (Li $$^+$$ -Li $$^+$$ )Kr $$_n$$ structures modeled with analytical potential energy surfaces and obtained through an optimization strategy is 19 for argon and 16 for krypton. Most of the structures have elongated shapes, associated with very long Li $$^+$$ -Li $$^+$$ distances, which may vary significantly from one size to the other. The lowest-energy metastable structure obtained for the smaller clusters, as well as the energy path for the dissociation of (Li $$^+$$ -Li $$^+$$ )Ar $$_{29}$$ , has been confirmed by re-optimization at the DFT level of theory.