Ground-state geometries and the stability of some clusters Li_nAl_m investigated using density-based ab initio molecular dynamics

Abstract

Density-based ab initio molecular dynamics has been used to investigate the stability and ground-state geometries of heteronuclear clusters of Li₇Al_n (n=1,7) and Li_nAl (n=1,8). Our investigations of these clusters indicate that the s - p bonded electrons favour a tetrahedral coordination, which plays a significant role in stabilizing the geometries of these clusters. We also report a remarkable ground-state structure for the Li₈Al₆ cluster, namely a face-centred cube with the Al atoms at the face centres forming an octahedron and Li atoms at the corners of the cube. The stability analysis based on the energetics shows that these clusters do not conform to the magic shell numbers observed for homonuclear alkali atom clusters.