▎ 摘　　要

We investigated nanoplasmon dynamics in graphene flake (GF) monomers and dimers using real-time and real-space time-dependent density functional theory. By showing the characteristic features of dynamical polarizability, we verified that the two distinct peaks in the optical absorption spectra can be attributed to pi and pi + sigma plasmons. We clearly show a significant difference between the on- and off-resonance responses of the p plasmon by demonstrating the spatial distribution of the induced charge and the electric field. We thus reveal the mechanism of plasmon-induced field enhancement near GF edges, which shows great importance of first-principles studies on molecular nanoplasmonics. (C) 2015 The Japan Society of Applied Physics