科研之友
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摘要
Recently, a grossly warped nanographene C80H30 has been synthesized experimentally. Its optical properties are studied and compared with bucky ball C-60, C-70, and a flat nanographene C78H30 in the framework of density functional theory (DFT) with the B3LYP functional. The static polarizability alpha, first-order hyperpolarizability beta, and second-order hyperpolarizability gamma are calculated using the finite field approach. The average values of and <gamma > for C80H30 are 151.7 angstrom(3) and 54.5 x 10(-35) esu, respectively, much higher than those of C-60 and C-70. Both and <gamma > 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 a along the z axis of C80H30 is 86.2 angstrom(3), much higher than 30.7 angstrom(3) of C78H30. Furthermore, the values of the hyperpolarizability in the z direction (gamma(xxzz), gamma(yyzz) and gamma(zzzz)) 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.
