无限长掺杂Zn棱柱型硅纳米管的理论研究

摘要

运用密度泛函方法在（U）B3LYP/LanL2DZ水平上研究了无限长四棱柱、五棱柱和六棱柱型掺杂锌的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,无限长四、六棱柱型Zn-Si纳米管的最低能结构均保持着基本的管状结构,五棱柱型的则畸变严重。五棱柱和六棱柱型Zn-Si纳米管的最低能结构的电子自旋多重态都为五重态,而四棱柱的为单重态。五棱柱型Zn-Si纳米管是这三种纳米管中热力学稳定性最强的。四、六棱柱型Zn-Si纳米管中电子从硅原子转向Zn原子,Zn原子充当电荷的受体,出现了电子反转现象。五棱柱型Zn-Si纳米管电子的转移方向比较复杂,Zn原子的位置不同,充当不同的电荷角色。两边的Zn原子是电荷的施体,而中间的则充当了电荷的受体。无限长掺杂Zn的五棱柱型硅纳米管的HOMO-LUMO能隙比较大,它的化学稳定性比较强。这三种纳米管呈半导体型。虽然这三种纳米管是极性的,但是五棱柱型的极性很弱。%The geometric structures,charge population,HOMO-LUMO gap and electric dipole moment of the quadrangular,pentagonal and hexagonal prism-silicon nanotube doped with zincum atoms are investigated computationally by density functional method at the（U）B3LYP/ LanL2DZ level.The results calculated indicate that the structure of the lowest-energy of the quadrangular and hexagonal prism-Zn-Si nanotube keep the similar framework of the tube,but the pentagonal prism-Zn-Si nanotube distorted seriously.The spin configurations of the lowest-energy structure of prism-Zn-Si nanotube are quintet.The calculated atomic averaged binding energies manifest that the structure of the pentagonal prism-Zn-Si nanotube is most stable in the three kinds of the Zn-Si nanotube.Meanwhile,Mulliken populations indicate that charges transfer mainly from Si atoms to Zn atoms in the lowest-energy structure of the quadrangular and hexagonal prism-Zn-Si nanotube.Zn atoms are acceptor,but charge transfer is complex in the pentagonal prism-Zn-Si nanotube.The HOMO-LUMO gap of the pentagonal prism-Zn-Si nanotube is bigest,which revealed that its chemical stability strongest in the three kinds Zn-Si nanotube.The electric dipole moment of the three kinds of the prism-Zn-Si nanotube isn＇t 0 means their structures are polar,but the polar of the pentagonal prism-Zn-Si nanotube is weak.