New Concepts of Metallic Bonding Based on Valence-Bond Ideas

Abstract

From generalized-valence-bond calculations on numerous Li-atom clusters (${\mathrm{Li}}_{n}$ and ${{\mathrm{Li}}_{n}}^{+}$, $n<~13$), we conclude that the optimum bonding involves singly occupied orbitals localized interstitially (in tetrahedra). Rules based on the calculations are used to predict low-energy isomers (leading for ${\mathrm{Li}}_{13}^{+}$ to low-symmetry structures that are significantly more stable than the icosahedron but retain local fivefold-symmetry axes) and are applied to infinite metallic systems.