中文摘要：

基于密度泛函理论（DFT）的DMol^3软件包，研究了（9，0）型碳纳米管（CNT）顶端掺杂B／N／Si等元素对其几何结构及电子结构的影响。结果表明，掺杂原子对非掺杂区几何结构影响微弱；加电场后，各种掺杂CNT顶端局域态密度（LDOS）峰位向价带移动；B／N／Si掺杂不仅引起CNT费米能级（E1）处LDOS增大，而且最低空轨道与最高占有轨道的差值（LUMO-HOMO）降低。由此可预期CNT顶端掺B／N／Si均有利于场致电子发射，且改善幅度依次增强。

英文摘要：

The influence of B/N/Si doping and applied electric field on the geometrical and electronic structures of （9,0） carbon nanotube （CNT） is investigated through the calculations of DMol^3 software package based on density functional theory （DFT）. The results indicate that the doped atoms have little effect on the geometrical structure of undoped region of CNT. When the external electric field is applied, the peak position of systems＇ LDOS shifts to the valance band, and the B/N/Si atoms cause the increment of LDOS at E1 and decrement of LUMO-HOMO gap. It is expected that the CNTs doping with B/N/Si be propitious to the electron field emission and the margin of improvement increases in turn.