Stability analysis of lithio-silicon Si10Li8 clusters: Planar bicyclic ring vs. three-dimensional structures

After exploration of the potential energy surface for the stoichiometry of Si10Li8 a three-dimensional motif was found as the most stable in comparison with planar and quasi-planar structures. The new minimum can be seen as the resulting of the interaction of three fragments: Si2⋯Li4⋯Si8Li4 stabilized by strong electrostatic interactions. In order to understand the stability both polarizability and aromaticity were studied. In general, the structural transition from planar or quasi-planar to three-dimensional structures increases the stability while decreases the polarizability of the system, in agreement with the minimum polarizability principle.