Pt-Ni合金团簇的结构与磁性的第一性原理研究

First-principles Study on the Pt-Ni Bimetallic Clusters

采用基于密度泛函理论的第一性原理计算程序包VASP(Vienna ab-initio Simulation Package)对Pt13,Ni13及Pt-Ni合金二十面体团簇进行了计算机模拟研究.研究表明,Pt13和Ni13团簇显现出完美的Ih(正二十面体)对称性,Pt13团簇的磁矩为2.13μB,Ni13团簇的平均原子磁矩也比其体块的原子磁矩有所增大.对Pt-Ni合金团簇,Pt原子倾向于偏析到团簇表面,团簇的平均最近邻键长随着Ni原子数目的增多而单调减小,总磁矩可通过Ni含量的变化而进行调制.

Using first-principles simulation package VASP（the Vienna ab-initio Simulation Package）, the Pt13 and Ni13 icosahedral clusters, as well as the Pt-Ni bimetallic icosahedral clusters are studied systematically. It is found that the optimized Pt13 and Ni13 clusters both show prefect Ih symmetry. The magnetic moment of Pt13 is 2.13 μB, although the bulk Pt is nonmagnetic. The average atomic magnetic moment of Ni in the Ni13 is also enhanced as compared with that of bulk Ni. For the Pt- Ni bimetallic cluster, the Pt atoms prefer to segregate to the surface of the cluster, and the average length of nearest neighbor- ing bonds decreases monotonically with the increase of nickel concentration. The total magnetic moment of the Pt-Ni cluster can be tuned by changing the Ni concentration.