Ab initio investigation of electronic structure, equilibrium geometries, and finite-temperature behavior of Sn-doped Li_n clusters

Abstract

A systematic investigation of the equilibrium geometries, nature of bonding, and stability has been carried out for Sn-doped Li clusters, Li_nSn, (1<~n<~9), by employing ab initio density-functional molecular dynamics. The Li₄Sn cluster with strong ionic bonds is found to be the most stable. The systematics of the energetics and charge density indicates a change in the nature of bonding from ionic to delocalized metalliclike, after n=6. The impurity atom, viz., Sn, is seen to induce significant changes in the geometries of host Li_n clusters. Sn does not get trapped and has a maximum of sixfold coordination with Li atoms. By carrying out finite-temperature isokinetic simulations for Li₆Sn and Li₇ at two temperatures, 100 and 300K, we demonstrate a rather dramatic change in the low-temperature behavior of the Sn-doped Li cluster.