Geometries, stabilities, and electronic properties of different-sized ZrSin (n=1-16) clusters: A density-functional investigation

摘要

The ZrSin (n=1-16) clusters with different spin configurations have been systematically investigated by using the density-functional approach. The total energies, equilibrium geometries, growth-pattern mechanisms, natural population analysis, etc., are discussed. The equilibrium structures of different-sized ZrSin clusters can be determined by two evolution patterns. Theoretical results indicate that the most stable ZrSin (n=1-7) geometries, except ZrSi3, keep the analogous frameworks as the lowest-energy or the second lowest-energy Sin+1 clusters. However, for large ZrSin (n=8-16) clusters, Zr atom obviously disturbs the framework of silicon clusters, and the localized position of the transition-metal (TM) Zr atom gradually varies from the surface insertion site to the concave site of the open silicon cage and to the encapsulated site of the sealed silicon cage. It should be mentioned that the lowest-energy sandwichlike ZrSi12 geometry is not a sealed structure and appears irregular as compared with other TM@Si-12 (TM=Re,Ni). The growth patterns of ZrSin (n=1-16) clusters are concerned showing the Zr-encapsulated structures as the favorable geometries. In addition, the calculated fragmentation energies of the ZrSin (n=1-16) clusters manifest that the magic numbers of stabilities are 6, 8, 10, 14, and 16, and that the fullerenelike ZrSi16 is the most stable structure, which is in good agreement with the calculated atomic binding energies of ZrSin (n=8-16) and with available experimental and theoretical results. Natural population analysis shows that the natural charge population of Zr atom in the most stable ZrSin (n=1-16) structures exactly varies from positive to negative at the critical-sized ZrSi8 cluster; furthermore, the charge distribution around the Zr atom appears clearly covalent in character for the small- or middle-sized clusters and metallic in character for the large-sized clusters. Finally, the properties of frontier orbitals and polarizabilities of ZrSin are also discussed. (C) 2005 American Institute of Physics.