Structural and electronic properties of TaSin (n=1-13) clusters:: A relativistic density functional investigation

The TaSin (n=1-13) clusters with doublet, quartet, and sextet spin configurations have been systematically investigated by a relativistic density functional theory with the generalized gradient approximation available in Amsterdam density functional program. The total bonding energies, equilibrium geometries, Mulliken populations as well as Hirshfeld charges of TaSin (n=1-13) clusters are calculated and presented. The emphasis on the stabilities and electronic properties is discussed. The most stable structures of the small TaSin (n=1-6) clusters and the evolutional rule of low-lying geometries of the larger TaSin (n=7-13) clusters are obtained. Theoretical results indicate that the most stable structure of TaSin (n=1-6) clusters keeps the similar framework as the most stable structure of Sin+1 clusters except for TaSi3 cluster. The Ta atom in the lowest-energy TaSin (n=1-13) isomers occupies a gradual sinking site, and the site moves from convex, to flatness, and to concave with the number of Si atom varying from 1 to 13. When n=12, the Ta atom in TaSi12 cluster completely falls into the center of the Si frame, and a cagelike TaSi12 geometry is formed. Meanwhile, the net Mulliken and Hirsheld populations of the Ta atom in the TaSin (n=1-13) clusters vary from positive to negative, manifesting that the charges in TaSin (ngreater than or equal to12) clusters transfer from Si atoms to Ta atom. Additionally, the contribution of Si-Si and Si-Ta interactions to the stability of TaSin clusters is briefly discussed. Furthermore, the investigations on atomic averaged binding energies and fragmentation energies show that the TaSin (n=2,3,5,7,10,11,12) clusters have enhanced stabilities. Compared with pure silicon clusters, a universal narrowing of highest occupied molecular orbital-lowest unoccupied molecular orbital gap in TaSin clusters is found. (C) 2004 American Institute of Physics.