摘要
采用密度泛函理论（DFT）方法系统研究了表面吸附碱金属Li原子的超短碳纳米管（[8]cyclophenacene）体系的结构和非线性光学性质.在这些体系中,Li原子均能稳定地吸附在超短碳纳米管表面,其吸附能高达84.0-106.2 kJ/mol.当吸附1-2个Li原子时,Li原子和碳纳米管之间发生了明显的电荷转移过程,使体系的一阶超极化率（β0）值明显改善,β0值从0迅速增加到3.42×10^3-8.29×10^3a.u.;当吸附的Li原子数增加到3时,体系内部产生了额外电子,有效地降低了体系最主要跃迁的跃迁能,使体系的一阶超极化率进一步提升（高达2.59×10^6a.u.）.此外,Li原子之间的距离也是影响吸附体系β0值的重要因素.
Under the density functional theory（ DFT） method,the structures and nonlinear optical（ NLO）properties of seven new Lin@ cyclophenacene（ n = 1—3） species were investigated in detail,where one to three Li atoms are adsorbed over the surface of the super-short carbon nanotube（ [8]cyclophenacene）. In these systems,the Li atoms can be adsorbed stably on the nanotube,as revealed by their considerable adsorption energies（ 84. 0—106. 2 kJ /mol）. Besides,when adsorbing one to two alkali Li atoms,the first hyperpolarizability of the carbon nanotube can be effectively improved,where the β0value can be significantly increased from zero to the range of 3. 42 × 10^3—8. 29 ×10^3a. u.,owing to the occurrence of charge transfer process from the Li atom to the nanotube. Comparatively,when increasing the number of the adsorbed Li atoms to three,the β0value can be further enhanced sharply,even to as large as 2. 59 × 106 a. u.,which can be attributed to the formation of the excess electron. Moreover,the distance between the adsorbed Li atoms can also play an important role in effecting the first hyperpolarizabilities of systems. This work can provide some new valuable insights for designing the new type of high-performance NLO materials based on the carbon nanotubes.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
2014年第11期2390-2396,共7页
Chemical Journal of Chinese Universities
基金
国家自然科学基金(批准号:21103065
21373099
21173097)
国家'九七三'计划项目(批准号:2012CB932800)
教育部博士点基金(批准号:20110061120024
20130061110020)资助~~
关键词
碱金属原子
超短碳纳米管
一阶超极化率
电荷转移
额外电子
表面吸附
非线性光学性质
Alkali metal atom
Super-short carbon nanotube
First hyperpolarizability
Charge transfer
Excess electron
Surface-adsorption
Nonlinear optical property
