Geometries and magnetisms of the Zr-n (n=2-8) clusters: The density functional investigations

摘要

The geometries, stabilities, and electronic and magnetic properties of small-sized Zr-n (n=2-8) clusters with different spin configurations were systematically investigated by using density functional approach. Emphasis is placed on studies that focus on the total energies, equilibrium geometries, growth-pattern behaviors, fragmentation energies, and magnetic characteristics of zirconium clusters. The optimized geometries show that the large-sized low-lying Zr-n (n=5-8) clusters become three-dimensional structures. Particularly, the relative stabilities of Zr-n clusters in terms of the calculated fragmentation energies and second-order difference of energies are discussed, exhibiting that the magic numbers of stabilities are n=2, 5, and 7 and that the pentagonal bipyramidal D-5h Zr-7 geometry is the most stable isomer and a nonmagnetic ground state. Furthermore, the investigated magnetic moments confirm that the atomic averaged magnetic moments of the Zr-n (n not equal 2) display an odd-even oscillation features and the tetrahedron C-s Zr-4 structure has the biggest atomic averaged magnetic moment of 1.5 mu(B)/at. In addition, the calculated highest occupied molecular orbital-lowest unoccupied molecular orbital gaps indicate that the Zr-n (n=2 and 7) clusters have dramatically enhanced chemical stabilities.