A systematic investigation of the geometries, electronic and magnetic properties of AlnAsq (q =-1, 0,+1; n=1-16) clusters: a DFT calculation

The geometries, electronic and magnetic properties of AlnAsq (q=-1,0,+1; n=1-16) clusters have been investigated systematically by using an unbiased CALYPSO structure searching method and density functional theory. The lowest energy structures show that the As atom prefers to occupy, the peripheral position of Aln+1 clusters instead of the endohedral position. For cationic and neutral clusters, the structural transition from bilayer-like structure to cage-like structure is observed at cluster size n=12, while it occurs at n=13 for anionic clusters. The calculated detachment energies (DEs), ionisation potentials (IPs) and electronic affinities (EAs) are consistent with the available experimental and theoretical results for small clusters, indicating that the calculated lowest energy structures are reliable. Furthermore, the DE, EA and IP values for cluster size n >= 6 are successfully predicted. A stability analysis shows that Al5As and Al12As+ clusters have relatively large HOMO-LUMO energy, gaps, corresponding to the magic numbers of 20 and 40 valence electrons, respectively. [GRAPHICS] .