AN AB-INITIO MOLECULAR-DYNAMICS INVESTIGATION OF LINALN CLUSTERS

A systematic investigation of the ground-state geometries and stabilit ies of LinAln (n = 1-10 and 13) clusters made by employing ab initio d ensity-based molecular dynamics is reported. Although in the solid-sta te form, the 50:50 alloy takes on a B32-ordered structure, no evidence for such ordering has been seen for small clusters. Instead there is a clustering tendency of the Al atoms, and they tend to form inner clu sters whose geometries are different from those of the free Al cluster s. The Li and Al atoms favour a tetrahedral coordination due to the si gnificant role of the s-p bonding of the electrons. A stability analys is based on energetics shows that the stability is enhanced in cluster s where all of the Al faces have been capped by Li atoms, and this giv es some remarkably interesting geometries, like the face-centred-cubic structure of LigAl6.