Excitation of intrinsic localized modes in a graphene sheet

¹  Research and Development Center, Toshiba Corporation - 1, Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa 212-8582, Japan
²  Department of Mechanical Engineering and Science, Kyoto University - Yoshida-hommachi, Sakyo-ku, Kyoto-shi, Kyoto 606-8501, Japan
³  Department of Adaptive Machine Systems, Osaka University - Suita, Osaka 565-0971, Japan

Received: 14 May 2007
Accepted: 26 September 2007

Abstract

In order to examine the excitation of intrinsic localized modes (ILMs) in a real material, we analyze two-dimensional vibration of a graphene sheet using molecular-dynamics simulations based on the Brenner potential. Energy localization is observed in a few regions for 1.0 ps. Fairly constant vibration modes, in which the two neighboring atoms vibrate in the opposite direction, are generated locally. The frequency of the localized vibration exceeds the upper bound of the phonon band and the mode is similar to one of the eigenmodes. The localized vibration remains at the same location and maintains the mode for a fairly long time (26 cycles). Since all of these results correspond to the characteristic features of ILM, it is concluded that the stationary ILM is excited in the graphene sheet.