Sn_nSm(n=1～9)团簇结构稳定性与磁学性质的理论研究

Theoretical Studies on the Structure Stability and Magnetic Properties of Sn_nSm( n = 1—9) Clusters

采用Saunders全局优化随机踢球模型与密度泛函理论相结合的方法,在B3LYP/SDD理论水平下研究了锡基原子团簇Snn（n=2-10）及锡基稀土原子钐掺杂团簇SnnSm（n=1-9）的几何结构、稳定性、电子性质和磁性.结果表明,团簇SnnSm（n=1-9）中掺杂的钐原子通常位于主团簇的表面,掺杂团簇的基态结构更倾向于具有较高对称性的三维结构;二元锡基混合团簇的平均结合能变大,稳定性增强,这主要归因于Sn—Sm键比Sn—Sn键的键能大,具有更强的相互作用;掺杂团簇具有较高的磁性,其总磁矩主要源自于钐原子4f电子的贡献;随着团簇尺寸的增加,二元团簇的总磁矩呈现出趋于饱和的现象.

The geometrical structures,relative stabilities,electronic properties and magnetism of tin clusters and bimetallic complexes of tin clusters with one samarium atom SnnSm（ n = 1—9） were investigated with the Saunders ＂Kick＂global stochastic search technique combined with density functional theory（ DFT） calculations at the B3 LYP / SDD level of theory. The results are as follows：（ 1） Samarium atom usually located on the surface in the doped tin-based with one samarium atom clusters. And the ground-state structures of the SnnSm（ n =1—9） clusters prefer to three-dimensional structure with higher symmetry;（ 2） after doping samarium atom in the Sn-based cluster,the cluster has the increase average binding energy which should owe to the fact that the bonding energy of Sn—Sm bond is higher than Sn—Sn bond and has the stronger interaction;（ 3） the doped Sn-based with one samarium atom cluster has large magnetic moments,and the contribution of magnetic moment almost comes from 4f electron orbit of the samarium atom,while the contribution of tin atoms is negligible. With the increase of cluster＇s size,bimetallic complexes cluster has the special phenomenon that the total magnetic moment tends to be stable.