第一性原理计算ZrnFe(n=2—13)团簇的基态结构及其磁性

从第一性原理出发，利用密度泛函理论中的广义梯度近似对Zr_nFe(n=2—13)团簇进行了结构优化、能量和频率计算.在充分考虑自旋多重度的前提下，对每一具体尺寸的团簇，得到了多个平衡构型，并根据能量高低确定了团簇的基态结构.综合团簇的结合能、二阶能量差分以及团簇的最高占据轨道和最低未占据轨道间的能隙可知Zr₅Fe，Zr₇Fe和Zr₁₂Fe团簇的稳定性相对较高，Zr₁₂Fe团簇的结构是具有I_h对称性的正二十面体，而且Zr₁₂Fe的稳定性在所有团簇中是最高的.另外，不仅Zr₅Fe，Zr₇Fe和Zr₁₂Fe团簇的稳定性相对较高，而且它们均为磁性团簇(而Zr_n团簇的磁矩在n≥5时已经发生了淬灭)，由此可知通过选择合适的掺杂元素可能得到高稳定的磁性团簇.从Mulliken布居分析结果可知，除了在Zr₁₂Fe团簇中Fe原子失去少量电荷外，其他团簇中Fe原子均从Zr原子那里得到了一定量电荷，即Fe原子在Zr_nFe(n=2—13，n≠12)团簇中是电子受体.

First principles study of the ground-state structures and magnetism of ZrnFe

The geometries，total energies，and frequencies of Zr_nFe(n=2—13)clusters have been systematically investigated by using density functional theory with the generalized gradient approximation, and the equilibrium geometries at different spin multiplicities as well as the ground-state structures have been determined. The calculated results of the averaged binding energy, the second-order difference of cluster energies as well as the HOMO-LUMO gap of the Zr_nFe(n=2—13) clusters indicate that the relative stabilities of Zr₅Fe, Zr₇Fe and Zr₁₂Fe are stronger than that of other sized clusters. The true ground state for Zr₁₂Fe cluster has icosahedral structure with I_h symmetry, and moreover, the stability of Zr₁₂Fe is strongest among all the investigated clusters. In addition, not only the relative stabilities of Zr₅Fe, Zr₇Fe and Zr₁₂Fe clusters are stronger than other sized clusters, but also they are all magnetic clusters (however, the magnetic moment of Zr_n clusters is quenched for n≥5), thus it can be seen thant we can acquire magnetic clusters with higher stabilities by choosing appropriate doping atom. Mulliken population analysis shows that there is a weak charge transfer from Zr atoms to Fe atom except for Zr₁₂Fe cluster, in which a small amount of charge transfers from Fe atom to Zr atoms.