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运用密度泛函方法在(U)B3LYP/LanL2DZ水平上研究了四棱柱、五棱柱、六棱柱和七棱柱型封装Cd硅纳米管的几何结构、电荷布局、能级和电偶极矩.计算结果表明,四棱柱、六棱柱和七棱柱型Cd硅纳米管的最低能结构都是自旋单重态,四棱柱和五棱柱型Cd硅纳米管畸变比较严重,已经失去管状结构.四棱柱型Cd硅纳米管的原子平均结合能最大,是这四种棱柱型Cd硅纳米管中热力学稳定性最强的.这四种棱柱型Cd硅纳米管的电荷都是由Cd原子转向Si原子的,Cd原子是电荷的施体;Si原子是电荷的受体,Cd原子与硅原子之间以共价键结合.五棱柱型Cd硅纳米管HOMO-LUMOGap最大,它的化学活性最强,而四棱柱型Cd硅纳米管的HOMO-LUMO能隙最小,它的化学稳定性最强,不易和其他物质发生化学反应.四棱柱型Cd硅纳米管的总电偶极距为零,该结构是非极性的,而五棱柱、六棱柱和七棱柱型Cd硅纳米管是极性的,且五棱柱型Cd硅纳米管的极性最强.
The geometrical structures, charge distributions, energy levels and electric dipole moments of CdSi nanotubes encapsulated in tetrapods, pentagons, hexagons and heptagonal prismatic packages were investigated by density functional theory at (U) B3LYP / LanL2DZ level. The results show that the lowest energy structures of the tetrahedral, hexagonal and heptagonal CdSNTs are all spin singlet states, and the distortions of the tetrahedral and pentagonal CdS nanotubes are relatively serious and the tubular structure has been lost. Silicon nanotubes have the highest average atomic binding energies and are the most thermodynamically stable among the four prismatic Cd-doped silicon nanotubes.The charges of the four prismatic Cd-doped silicon nanotubes are all from Cd to Si, and Cd Atoms are charge donors, Si atoms are charge acceptors, and Cd atoms and silicon atoms are covalently bonded. The pentagonal CdSi nanotubes HOMO-LUMOGap is the largest and its chemical activity is the strongest. Type Cd-Si nanotubes have the smallest energy gap and the highest chemical stability, which makes it difficult to chemically react with other substances. The total dipole pitch of the prismatic Cd-Si nanotubes is zero and the structure is nonpolar While pentagonal, hexagonal and heptagonal Cd-doped silicon nanotubes are polar The pentagonal Cd-Si nanotubes are the most polar.