新设计的碳纳米管锂盐的第一超极化率的理论研究

Theoretical Study on the First Hyperpolarizability of New Lithium Salt(Li-CNTs)

利用B3LYP/6-31G(d)方法对设计的30个碳纳米管锂盐(Li-CNT)进行了结构优化和频率分析,并采用BHandHLYP/6-31G(d)方法计算了体系的第一超极化率.结果表明,锂原子掺杂的碳管具有较大的第一超极化率.当碳管径适当时,体系的第一超极化率随着管径的增加而增加.碳管的长度、极化率、电子延展广度R2和跃迁能ΔE对体系的第一超极化率β有一定的影响.另一方面,一些体系的分子第一超极化率与双能级模型吻合较好.

The geometries of 30 lithium salts（Li-CNTs） are optimized at the B3LYP/6-31G（d） level and frequency analysis confirms that the optimized structures are stable.Then,the first hyperpolarizabilities of these structures are calculated at the BHandHLYP/6-31G（d） level of theory.The results demonstrate that lithium-doped carbon tubes have large first hyperpolarizability.For suitable tube diameter,the first hyperpolarizabilities increase with the increasing of tube diameter.Also,the length of CNTs,the polarizabilities α,electronic spatial extent R2,and transition energy have some influence on the first hyperpolarizability.On the other hand,the first hyperpolarizabilities of some systems satisfy two-level model very well.