Equilibrium geometries and electronic properties of Be_nLi (n=2--15) clusters from first principles

This paper studies the equilibrium geometries and electronic properties of Be_n and Be_nLi clusters, up to n=15, by using density-functional theory(DFT) at B3LYP/6--31G(d) level. The lowest-energy structures of Be_n and Be_nLi clusters were determined. The results indicate that a single lithium impurity enhances the stability and chemical reactivity of the beryllium clusters. It finds that the geometries of the host clusters change significantly after the addition of the lithium atom for n \ge 8. The lithium impurity prefers to be on the periphery of beryllium clusters, and occupies vertex sites. Both Be_4Li, Be_9Li, and Be_13Li were found to be particularly stable with higher average binding energy, local peaks of second-order energy difference and fragmentation energies. For all the Be_nLi clusters studied, we found charge transfers from the Li to Be site and co-existence of covalent and metallic bonding characteristics.