Structure, electronic and magnetic properties of (ZnSe)₁₂ clusters doped with one or two Mn atoms were studied with a first-principles method. Substitutional, exohedral, and endohedral doping are considered. Substitutional isomers are found most favorable for both monodoped and bidoped clusters. Magnetic moment is mainly contributed by 3d component of Mn atom, while 4s and 4p orbitals also have certain contributions. Due to hybridization interaction, a small magnetic moment is induced in nearest neighboring Se and Zn atoms. We demonstrate that endohedral bidoped (ZnTe)₁₂ clusters favor ferromagnetic state, which has potential applications in nanoscale quantum devices.

Structures and magnetic properties of Cr monodoped and bidoped single-wall ZnS nanotubes are studied with firstprinciples calculations. Formation energies of doped nanotube are lower than those of pristine ones, indicating that doing process is an exothermic reaction. Doped nanotubes have atom-like magnetic moments mainly due to 3d component of Cr atoms. Our results indicate that Cr-doped ZnS nanotubes tends to adopt ferromagnetic (FM) configuration. Energy differences between FM and antiferrimagnetic (AFM) is only 36 meV. To obtain room temperature ferromagnetism, we replace one S atom by C atom. Its FM states are lower in energy than AFM states by 497 meV. Such large energy differences imply that room temperature ferromagnetism could be expected.

Magnetic properties of single-wall ZnS nanotubes (NTs) doped with Fe atoms are studied with first-principles calculations.Formation energies of doped NTs are smaller than that of pristine one,which indicating that doping is an exothermic reaction.Monodoped NTs has atom-like magnetic moments mainly due to 3d component of Fe atoms.It indicates that Fe-doped ZnS NTs tend to adopt antiferromagnetic (AFM) configurations.To obtain room temperature ferromagnetism,we replaced an S atom by a C atom and found that C atom prefers to substitute S atom connecting two Fe atoms.Ferromagnetic (FM) state energy is lower than that of AFM state by 164 meV.It implies that room temperature ferromagnetism is expected in these systems.

We study systematically structural and electronic properties of ZnO/ZnS superlattice nanowires and core-shell structural ZnO/ZnS nanowires with first-principles calculations. Relaxed structures of these heterostructural nanowires are found similar to those of homogeneous ZnO and ZnS nanowires. Band structures of heteronanowires show that they are direct-band gap semiconductors. For ZnO/ZnS superlattice nanowires, bands become flatter with the formation of minibands. For core-chell ZnO/ZnS nanowires, PDOS show that they are type-Ⅱ heterostructures. These may be important in understanding structural and electronic properties of heterostructural nanowires and their utilization in electric generator and photovoltaic devices.

Structure and magnetic properties of (ZnO)₁₂ clusters doped with one (monodoped) and two (bidoped) Co atoms are studied with first-principles method. Substitutional, exohedral, and endohedral doping are considered. Exohedral isomers are found the most favorable in both monodoped and bidoped clusters. Magnetic coupling between Co atoms is short-range. Magnetic coupling between Co atoms at the nearest neighbor is mainly governed by competition between direct Co-Co antiferromagnetic interaction and ferromagnetic interaction between two Co atoms via O atom due to strong p-d hybridization. We demonstrate that exohedral bidoped cluster favors ferromagnetic state, which has potential applications in nanoscale quantum devices.

In this paper, we build the asymptotic expansion of solution of Du Fort-Frankel scheme for diffusion problem and then use extrapolation. The accruacy of the extrapolation solution may achieve O(τ²+h⁴) and the limitation of consistency is improved greatly.