title: The encapsulated lithium effect on the first hyperpolarizability of C60Cl2 and C60F2.
abstract: In this paper, we report a study on the structure and first hyperpolarizability of C60Cl2 and C60F2. The calculation results show that the first hyperpolarizabilities of C60Cl2 and C60F2 were 172 au and 249 au, respectively. Compared with the fullerenes, the first hyperpolarizability of C60Cl2 increased from 0 au to 172 au, while the first hyperpolarizability of C60F2 increased from 0 au to 249 au. In order to further increase the first hyperpolarizability of C60Cl2 and C60F2, Li@C60Cl2 and Li@C60F2 were obtained by introducing a lithium atom to C60Cl2 and C60F2. The first hyperpolarizabilities of Li@C60Cl2 and Li@C60F2 were 2589 au and 985 au, representing a 15-fold and 3.9-fold increase, respectively, over those of C60Cl2 and C60F2. The transition energies of four molecules (C60Cl2, Li@C60Cl2, C60F2, Li@C60F2) were calculated, and were found to be 0.17866 au, 0.05229 au, 0.18385 au, and 0.05212 au, respectively. A two-level model explains why the first hyperpolarizability increases for Li@C60Cl2 and Li@C60F2.
authors: College of Mathematics and Physics, Fujian University of Technology, Fuzhou, Fujian, 350118, People's Republic of China. yaodong909@163.com.
authors: Yao-Dong
authors: YD
authors: Song
authors: School of Humanities, Fujian University of Technology, Fuzhou, Fujian, 350118, People's Republic of China.
authors: Liang
authors: L
authors: Wang
authors: Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, People's Republic of China. liming_wu@fjirsm.ac.cn.
authors: Li-Ming
authors: LM
authors: Wu
authors: College of Mathematics and Physics, Fujian University of Technology, Fuzhou, Fujian, 350118, People's Republic of China.
authors: Qiao-Ling
authors: QL
authors: Chen
authors: College of Mathematics and Physics, Fujian University of Technology, Fuzhou, Fujian, 350118, People's Republic of China.
authors: Fa-Kun
authors: FK
authors: Liu
authors: College of Mathematics and Physics, Fujian University of Technology, Fuzhou, Fujian, 350118, People's Republic of China.
authors: Xiao-Wen
authors: XW
authors: Tang
keywords: First hyperpolarizability; Fullerene derivative; Transition energy