Density Functional Study of Nonlinear Optical Properties of Grossly Warped Nanographene C80H30

Abstract

Recently, a grossly warped nanographene C80H30 has been synthesized experimentally. Its optical properties are studied and compared with bucky ball C60, C70, and a flat nanographene C78H30 in the framework of density functional theory (DFT) with the B3LYP functional. The static polarizability α, first-order hyperpolarizability β, and second-order hyperpolarizability γ are calculated using the finite field approach. The average values of ⟨α⟩ and ⟨γ⟩ for C80H30 are 151.7 Å3 and 54.5 × 10–35 esu, respectively, much higher than those of C60 and C70. Both ⟨α⟩ and ⟨γ⟩ of planar C78H30 are higher than those of C80H30, which is consistent with the fact that the energy gap of C78H30 is smaller than that of C80H30. However, the diagonal component of α along the z axis of C80H30 is 86.2 Å3, much higher than 30.7 Å3 of C78H30. Furthermore, the values of the hyperpolarizability in the z direction (γxxzz, γyyzz, and γzzzz) of C80H30 are almost 1 order of magnitude higher than those of C78H30. The relationship between optical properties and electron delocalization in molecules indicated by aromaticity is also discussed. Our results indicate that C80H30 can be used as a promising optical material.