The encapsulated lithium effect of Li@C60Cl8 remarkably enhances the static first hyperpolarizability

Abstract

Recently, C₆₀Cl₈ (C_2v) has been experimentally synthesized (Y.-Z. Tan, et al., Nat. Mater., 2008, 7, 790) by the addition of eight chlorine atoms to C₆₀ (C_2v), which is associated with a Stone–Wales transformation of C₆₀ (I_h). In this work, the first hyperpolarizabilities (β_tot) of C₆₀ (C_2v) and C₆₀Cl₈ (C_2v) are investigated. After the Stone–Wales transformation and chlorine addition reaction, the β_tot values slightly increase from 0 for C₆₀ (I_h) to 60 au for C₆₀ (C_2v) and 502 au for C₆₀Cl₈ (C_2v), respectively. To further enhance the first hyperpolarizability, the endohedral fullerene derivative, Li@C₆₀Cl₈, formed by encapsulating a lithium (Li) atom inside the C₆₀Cl₈, has been designed. Interestingly, the electron transfer between Li and C₆₀Cl₈ leads to an extremely large β_tot value of 25 569 au, which is considerably larger (51 times) than the 502 au of C₆₀Cl₈. It shows that the encapsulated Li effect plays an important role in enhancing the first hyperpolarizability, so the Li@C₆₀Cl₈ can be considered as a candidate for high-performance nonlinear optical materials.