First-principles Studies Of Doped Clusters Cu₁₁X₂（X=3d Transition Metal Atoms）

By applying the ab-initio method based on density functional theory(DFT), the mixed neutral Cu11X2(X=Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn) clusters are calculated systematically by using the Dmol3 software. The main contents and conclusions are as follows:(1) The ground-state geometry of the mixed Cu11Sc2 cluster is a double hexagonal pyramid;The ground-state structures of Cu11X2(X=Ti、V、Cr、Mn、Fe) clusters are all closed-packing configurations with replacing the center atom and one surface atom. For the four high-symmetric(Ih, Oh, D5 h, D3h) closed-packing structures, the center-replacing atom containing doping structures are all more stable than the double surface-replacing doping structures; Ground-state structures of Cu11Co2, Cu11Ni2 and Cu11Zn2 are same as that of the pure Cu13 cluster. We speculate that: The reason that the ground state structures of doping clusters Cu11Co2, Cu11Ni2 and Cu11Zn2 are disorderly loosely configurations is caused by its special electronic structure(rather than the geometry effect). The geometric structure factor has obvious effect on the ground-state structures of the doping clusters Cu11X2(X = Ti, V, Cr, Mn, Fe).(2) There has obvious isomerism for the ground-states of the mixed clusters Cu11X2(X = Sc, Co, Zn), while no obvious isomerism can be found for the ground-states of the Cu11X2(X=Ti、V、Cr、Mn、Fe、Ni) clusters. With the comparison to the ground-state of Cu13 and the ground-states of those single-atom doping clusters Cu12 X, the stabilities, energy gaps and magnetic moments of the Cu11X2 clusters are all enhanced in general. It reflects that increasing the number of impurity atoms is favorable to improve the stability of clusters and enhance the magnetism of the clusters.(3) Vatiation of the magnetic moment with the cluster symmetry shows normal dependence(low symmetry corresponds to low magnetic moment) for the Cu11X2(X = Sc, Ni, Zn) clusters. And for the other doped clusters, the abnormal dependence can be found in general between the magnetic moment and the cluster symmetry(high symmetry corresponds to low magnetic moment, and low symmetry corresponds to high magnetic moment), which reflects the complexity between cluster magnetism and the other factors like the cluster geometry and its electronic structure.