Co@Au_n(n=1～8)团簇的几何结构和电子性质的理论研究

本文利用密度泛函PW91方法研究了Co@Au_n（n=1～8）团簇的平衡结构、稳定性和磁矩.结构优化显示Co原子在低能异构体中趋于占据最高配位位置,基态Co@Au_n（n=2～6）团簇为二维结构,Co@Au₇和Co@Au8转变为三维结构.原子平均结合能、二阶能量差分及HOMO-LUMO能级间隙分析表明掺杂Co原子提高了金团簇的稳定性,改变了金团簇能级间隙的奇偶振荡性,n=5为掺杂团簇的幻数.磁矩的计算揭示Co@Au_n团簇的磁性主要源于Co原子的3d轨道.

Theoretical study of geometrical structures and electronic properties for Co@Aun(n=1-8) clusters

The equilibrium structures, stabilities and magnetic properties of Co@Aun (n=1-8) clusters have been investigated using density functional theory at the PW91 level. The structural optimizations show that the Co atom in low-energy isomers tends to occupy the most highly coordinated position. The ground-state Co@Aun clusters possess two-dimensional structure for n=2-6 and three-dimensional structure for n=7 and 8. The relative stabilities of the ground-state Co@Aun structures are analyzed based on the averaged binding energies, second-order difference of energies, and HOMO-LUMO energy gaps. It is found that Co atom improves the stability of host cluster and the Co@Au5 is magic cluster. The odd-even oscillation of energy gaps of gold clusters is changed by the Co atom. The magnetic moment calculations indicate that the total magnetic moment of Co@Aun clusters is mainly localized on the 3d orbital of Co atom