内掺过渡金属非典型富勒烯M@C22(M=Sc, Ti, V, Cr, Mn, Fe, Co, Ni) 几何结构、电子结构、稳定性和磁性的密度泛函研究

采用密度泛函理论中广义梯度近似对非典型富勒烯C₂₂和过渡金属内掺衍生物M@C₂₂(M=Sc,Ti,V,Cr,Mn,Fe,Co和Ni)的几何结构和电子结构进行计算研究.发现非典型富勒烯C₂₂的基态结构是含有一个四碳环的单重态笼状结构.过渡金属原子的掺入明显提高了体系的稳定性. C-M键既有一定共价性又有一定离子性.磁性、能级图、轨道分布和态密度图分析表明: M原子的3d轨道和碳笼的C原子的原子轨道之间存在较强的轨道杂化. Ti, Cr, Fe和Ni内掺的结构出现磁性完全猝灭现象. Sc和碳笼间是弱反铁磁作用, V,Mn和Co与碳笼间是弱铁磁作用.

Density functional calculations of geomatric structure, electronic structure, stability, and magnetic properties of transitional atom endohedral unclassical fullerene M@C22(M=Sc,Ti, V, Cr, Mn, Fe, Co and Ni)

The generalized gradient approximation (GGA) based on density functional theory(DFT) is used to analyze the structural and electronic properties of the unclassical endohedral fullerene M@C₂₂(M=Sc, Ti, V, Cr, Mn, Fe, Co and Ni). It is found that the ground-state structure of the unclassical fullerene C_{22 }is a spin singlet cage containing one four-membered ring and the doping of transition metal atom can obviously enhance the stability. It is discovered that the C-M bond have both the covalent and the ionic characteristics. The analyses of magnetism, energy levels, orbital wave functions and density of states show the hybridization between the 3d orbital of M atom and the C atomic orbital in C₂₂. In addition, Ti, Cr, Fe and Ni atoms become non-magnetic after they have been doped into the C₂₂.