▎ 摘　　要

Graphene quantum dots (GQDs) with unique and tunable physical properties have been the focus of considerable attention because of their potential for electronic and photonic applications. In this work, the electronic polarizability and second hyperpolarizability of hexagonal GQDs were investigated using density functional theory. The effects of size, substituent, and incident frequency of hexagonal GQDs on their electronic polarizability and second hyperpolarizability were comprehensively examined. Increasing the size of hexagonal GQDs enhanced the electronic polarizability and static second hyperpolarizability. The (hyper) polarizability of hexagonal GQDs was remarkably tuned by introducing electrondonor/acceptor groups and incident frequency. This study provides new possibilities for practical applications of graphene materials in the nonlinear optical field. (C) 2017 Elsevier Ltd. All rights reserved.