Theoretical study on third-order nonlinear optical properties in hexagonal graphene nanoflakes: Edge shape effect

Zigzag-edged hexagonal graphene nanoflake (Z-HGNF), which gives an intermediate diradical character (y), exhibits a large enhancement of orthogonal components of γ (γ ≡ γxxxx = γyyyy in this case) relative to armchair-edged hexagonal graphene nanoflake (A-HGNF), which gives zero y value (closed-shell system).