The geometries, stabilities, and electronic and magnetic properties of Sc(n)Al (n = 1-14) clusters with different spin configurations have been investigated systematically within the framework of the gradient-corrected density-functional theory. Our resulting geometries show that the aluminum atom remains on the surface of clusters with n<9, while it takes up the center of Sc-cage clusters with n≥9. Besides, the doping of Al improves the stability of the host clusters. Maximum peaks are observed for Sc(n)Al clusters at n = 3, 6, 10 and 12 with the size dependent on the second-order energy differences and fragmentation energies, implying that these clusters are relatively more stable. For all the Sc(n)Al clusters studied, we find the charge transfer from Sc to Al sites and the coexistence of ionic and covalent bonding characteristics. The doping of the Al atom induces the magnetic moments of the host clusters decrease except for n = 8 and 14 and the total magnetic moments are quenched at n = 5, 7, 9 and 11.
The lowest-energy structures and the electronic properties of CdnSn (n = 1–8) clusters have been studied by using density-functional theory simulating package DMol3 in the generalized gradient approximation (GGA). The ring-like structures are the lowest-energy configurations for n = 2, 3 and the three-dimensional spheroid configurations for n = 4 – 8. The three-dimensional structures may be considered as being built from the Cd2S2 and Cd3S3 rings. Compared to the previous reports, we have found the more stable structures for CdnSn(n = 7,8). Calculations show that the magic numbers of CdnSn (n = 1 – 8) clusters are n = 3 and 6. As cluster size increases, the properties of CdnSn clusters tend to bulk-like ones in binding energy per CdS unit and Mulliken atomic charge, obtained by comparing with the calculated results of the wurtzite and zinc blende CdS for the same simulating parameters.
The electronic structures of pure and Cd-doped wurtzite ZnO have been investigated by using first-principle ultrasoft pseudopotential approach of the plane wave. The calculation indicates that the band gap of ZnO is reduced by Cd doping. With increasing Cd-doping concentration, the lower energy states of Zn 4s orbital can take part in hybridization, so that the conduction band of minimum determined by the antibonding Zn 4s states can shift to the lower energy, and the energy of antibonding pd states which control the valence band of maximum becomes higher.
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