【摘要】 采用密度泛涵理论(densityfunctionaltheory,DFT)中的广义梯度近似(generallygradientapproximation,GGA)对富勒烯C72和内掺金属La富勒烯La2@C72三种同分异构体的几何结构和电子结构进行研究.发现在C72的三种同分异构体中,满足独立五边形规则(isolated-pentagon-rule,IPR)的C72(D6d)结构最为稳定;在La2@C72三种同分异构体中,有着两对两两相邻五元环(twofused-pentagon)的La2@C72(#10611)结构最为稳定,而满足IPR的La2@C72(D6d)的结构变成了最不稳定结构.从能级图和态密度图分析得知,笼子稳定性的变化与La原子的原子轨道与C72原子轨道之间的杂化有关.Mulliken电荷分析得知,La2@C72(#10611)的两个La原子共转移了约3个电子给C72,并且,它们几乎分布在整个C笼上,形成的电子结构为La32+@C372-.净自旋分析得知,La2@C72(#10611)中La原子磁性完全淬灭.更多还原

【Abstract】 The geometric and electronic properties of the three isomers for C- 72 and La-2@C- 72 have been studied using the generalized gradient approximation in density functional theory (DFT). It is found that C- 72 (D- 6d ) which satisfies the isolated-pentagon rule is the most stable structure among the three isomers of C- 72 , while La-2@C- 72 (#10611) is the most stable structure and La-2@C- 72 (D- 6d ) is the most unstable structure among the three isomers of La-2@C- 72 . It is also found from the analysis of energy levels as well as the density of states that the stability change is due to the mixing of La atomic orbital with C atomic orbital in C- 72 . From Milliken populations, we find that there are about three electrons transferring from the two encaged La atoms to C- 72 cage so the electronic configuration of La-2@C- 72 (#10611) can be described as La 3+ -2@C 3- - 72 . We also come to the conclusion from the net spins of La as well as of La-2@C- 72 that the magnetic moments of La have been completely quenched so La-2@C- 72 (#10611) shows no magnetism.更多还原