利用第一性原理密度泛函的方法对钠原子吸附闭口碳纳米管的场发射性质进行了综合研究，建立了(5，5)闭口碳纳米管吸附不同数量钠原子的吸附模型，并对加电场和未加电场下的模型进行了几何结构分析以及吸附能、离化能、局域态密度、Mulliken电荷分布的计算和分析。计算结果表明吸附能随着电场的增加而变大，吸附稳定性增强。吸附钠原子的碳纳米管在施加外电场后，费米能级附近的局域态密度随着钠原子的吸附而增加。钠原子在碳纳米管中的吸附可以在其尖端表面产生诱导偶极矩导致电荷由碳纳米管向钠原子大量转移，从而驱使电子由碳纳米管尖端发射到真空中，提高了碳纳米管的场发射性能。

We report a density functional theory (DFT) study regarding the effects of Na on field emission of single-wall carbon nanotubes (SWCNTs). Specifically, a comprehensive examination is carried out to investigate the effects of Na adsorbed on capped C(5,5) armchair SWCNT tips. A capped (5,5) carbon nanotubes model with different Na atoms adsorbed is built, and the adsorption energy, ionization potential, local density of states, Mulliken charge population of the model with and without the applied electric field are calculated and analyzed. The Mulliken charge population analysis shows that the charges are redistributed and accumulated on the tip. Under an applied electric field, the number of Mulliken charges that transfer from the carbon nanotube body to its tip increases with the increase of the number of Na atoms. The local density of states at the Fermi level increases with the adsorption of Na atoms. These results reveal that the field emission properties of carbon nanotubes can be enhanced by the adsorption of Na atoms.