Structural, electronic, and magnetic properties ofScn(n=2–18)clusters from density functional calculations

Abstract

The structural, electronic, magnetic properties of scandium clusters up to 18 atoms, within the framework of a gradient-corrected density functional theory, are reported. A number of low-lying isomers having different spin multiplicities are identified for each size. The clusters exhibit high stability at $n=4$, 7, 10, 13, and 16, a result which can be interpreted in terms of atomic motif and electronic ordering (within the elliptical spherical jellium model). The computed average magnetic moment per atom of the lowest energy structure oscillates with cluster size and is as high as $1.5{\ensuremath{\mu}}_{B}$ for ${\mathrm{Sc}}_{13}$. The measured magnetic moments are generally in accord with the average over different low-lying spin states of a given size. Ferromagnetic ordering is energetically preferred for smaller clusters with $n=2--8$ and competes with ferrimagnetic ordering in the medium sizes of $n=9--14$. Ferrimagnetic ordering is favored for larger sizes of $n=15--17$ and the first appearance of nonmagnetic state takes places at $n=18$, showing that the nonmagnetic character of bulk Sc is reached at relatively small cluster sizes.