Author/Authors :
Nagai، نويسنده , , Hiroshi and Nakano، نويسنده , , Masayoshi and Yoneda، نويسنده , , Kyohei and Fukui، نويسنده , , Hitoshi and Minami، نويسنده , , Takuya and Bonness، نويسنده , , Sean and Kishi، نويسنده , , Ryohei and Takahashi، نويسنده , , Hideaki and Kubo، نويسنده , , Takashi and Kamada، نويسنده , , Kenji and Ohta، نويسنده , , Koji and Champagne، نويسنده , , Benoît and Botek، نويسنده , , Edith، نويسنده ,
Abstract :
Using hybrid density functional theory methods, we investigate the second hyperpolarizabilities (γ) of hexagonal shaped finite graphene fragments, which are referred to as hexagonal graphene nanoflakes (HGNFs), with two types of edge shapes: zigzag (Z) and armchair (A) edges. It is found that Z-HGNF, which gives intermediate diradical characters (y), exhibits about 3.3 times larger orthogonal components of γ (γxxxx = γyyyy in this case) than A-HGNF, which gives zero y value (closed-shell system). The γ density analysis reveals that this enhancement originates in the significant contribution of γ densities on edge regions in Z-HGNF. These observations strongly indicate that Z-HGNF is a promising candidate of open-shell singlet NLO systems.
