笼状Au$lt;sub$gt;20$lt;/sub$gt;内掺$lt;i$gt;M$lt;/i$gt;$lt;sub$gt;13$lt;/sub$gt;($lt;i$gt;M$lt;/i$gt;=Fe，Ti)团簇磁性的密度泛函计算研究

采用密度泛函理论中的广义梯度近似方法，对M₁₃（M=Fe，Ti）以及M₁₃内掺Au₂₀团簇的几何结构和磁性进行了计算研究.结果表明：M₁₃和M₁₃内掺Au₂₀团簇的几何结构在0.006—0.05 nm误差范围内保持着I_h对称性.Fe₁₃团簇最低能态的总磁矩为44 μ_B，内掺到Au₂₀笼中后形成的Fe₁₃内掺Au₂₀团簇的最低能态总磁矩为38 μ_B，且Au原子与内掺Fe₁₃团簇之间存在着弱铁磁相互作用.Ti₁₃团簇在总磁矩为6 μ_B时能量最低，掺入Au₂₀笼后形成的Ti₁₃内掺Au₂₀团簇最低能态总磁矩是4 μ_B，内表面12个Ti原子与表面Au壳之间是弱铁磁相互作用，而与中心Ti原子之间是弱反铁磁相互作用.由于Au₂₀笼状外壳的影响，Fe₁₃内掺Au₂₀和Ti₁₃内掺Au₂₀团簇中Fe₁₃和Ti₁₃的磁矩比无金壳的Fe₁₃和Ti₁₃团簇的磁矩分别减少了6.81 μ_B和2.88 μ_B. 关键词： 几何结构 磁性 密度泛函理论

The magnetism of M13-doped cagelike structure of gold clusters (M = Fe, Ti)：density functional calculations

The geometric and magnetic properties of M₁₃ and M₁₃-doped Au₂₀ （M = Fe, Ti） clusters have been studied using the generalized gradient approximation based on the density functional theory. The optimized geometries of the clusters are close to the I_h structure within 0.006—0.05 nm tolerance. The lowest-energy spin states of the Fe₁₃ and Fe₁₃-doped Au₂₀ clusters are 44 μ_B and 38 μ_B, respectively, while there is week ferromagnetic interaction between the Fe and Au atoms for the Fe₁₃-doped Au₂₀ cluster. On the other hand, the lowest energy spin states of the Ti₁₃ and Ti₁₃-doped Au₂₀ clusters are 6 μ_B and 4 μ_B, respectively. The magnetic ordering is in a week ferromagnetic arrangement between the 12 surface Ti atoms and Au atoms, while in a week antiferromagnetic arrangement between the 12 surface Ti atoms and the core Ti atom. Comparing with the bare Fe₁₃ and Ti₁₃ clusters, the magnetic moments of Fe₁₃ and Ti₁₃ in Fe₁₃-doped Au₂₀ and Ti₁₃-doped Au₂₀ clusters are reduced by 6.81 μ_B and 2.88 μ_B, respectively.