Aluminum-lithium clusters: First-principles simulation of geometries and electronic properties

The geometries and electronic properties of small lithium-rich Al(N)Li(5N) (N=1-6,10) clusters are studied using first-principles simulations. Aluminum ions form a compact inner core configuration in the clusters that changes into a chainlike skeleton embedded in a lithium surrounding as the cluster size increases. This behavior restricts s-p hybridization effects and causes separate s and p bands in the electronic energy spectrum. A significant charge transfer from Li ions and nearby Al ions strengthens ionic Al-Li bonds, while Al-Al bonds gain a more covalent nature. The evolution of some bulk properties of B2 and B32 phases of AlLi alloys is studied by constructing 59- and 145-atom Al(N)Li(M) (Napproximate toM) clusters based on a truncated rhombic dodecahedron. Tetrahedrally coordinated covalent Al-Al bonds of B32 clusters affect the electronic properties and hardness.