Site-specific analysis of dipole polarizabilities of heterogeneous systems: iron-doped Si(n) (n = 1-14) clusters

Following the recent work of decomposing the total dipole moment and polarizability of a homogeneous system into site-specific contributions, we extend the study to the heterogeneous systems of iron-doped Sin (n = 1-14) clusters by introducing a weighting function. The structure-∕shape- and size-specific aspects of the dipole moments and polarizabilities of SinFe (n = 1-14) clusters are analyzed and compared with pure silicon clusters. It is shown that the polarizabilities associated with the individual constituent atoms vary considerably with the structure∕shape of the cluster and the location of the atom or site within a given structure. For atoms at peripheral sites, the polarizabilities are substantially larger than atoms at the interior sites, and the more peripheral an atom is, the larger is its polarizability. The polarizability of the Fe atom in SinFe clusters decreases as the cluster size increases. This is related to the position of Fe atom in SinFe clusters and indicates significant screening of the interior of the cluster by its surface. The correlation between the anisotropy of the total polarizability and the anisotropy of the cluster shape is also analyzed. Comparing with pure Sin clusters, the polarizabilities of Si atoms are increased after Fe atom doping. The structures are more compact for SinFe than the same sizes of Sin +1 clusters and the polarizabilities of SinFe are smaller than Sin +1 for the sizes of n = 7-14.