Geometric structures, electronic properties, and magnetism of M 2 Sn 17 ( M =Ni，Mn)and their anions

The geometric structures and magnetism of the three probable isomers for Ni 2 Sn 17 ，Mn 2 Sn 17 ，［Ni 2 Sn 17 ］ 4- and ［Mn 2 Sn 17 ］ 2- 　have been studied using the generalized gradient approximation based on density functional theory. It was found that the D 2 d structures of Ni 2 Sn 17 ，Mn 2 Sn 17 ，［Ni 2 Sn 17 ］ 4- and ［Mn 2 Sn 17 ］ 2- are the most stable structures among the three possible isomers. The study shows that the D 2 d structure and the D 4 d structure of Ni 2 Sn 17 have spin-splitting, leading to the magnetic moment 4 μ B and 2 μ B ， respectively, and there is weak ferromagnetic interaction between the Ni and Sn atoms for the D 2 d structure and the D 4 d structure. However, there is no magnetic moment in the D 4 h structure. On the other hand, the D 2 d , D 4 d , and D 4 h Mn 2 Sn 17 have 2 μ B ，6 μ B and 2 μ B magnetic moments, respectively. It is interesting that there is weak antiferromagnetic interaction and weak ferromagnetic interaction between Mn and Sn atoms for the D 2 d and D 4 h structures, respectively, while there is not only weak ferromagnetic interaction but also weak antiferromagnetic interaction between Mn and Sn atoms in the D 4 d structure. Finally, It is worth noting that all their anion counterparts of ［Ni 2 Sn 17 ］ 4- and ［Mn 2 Sn 17 ］ 2- have closed electronic configurations, showing no magnetic moment.