INSTITUTE OF PHYSICS PUBLISHING NANOTECHNOLOGY Nanotechnology 16 (2005) 583–589 doi:10.1088/0957-4484/16/4/041 Chaotic signature in the motion of coupled carbon nanotube oscillators V R Coluci 1 , S B Legoas 2 , M A M de Aguiar 1 and D S Galv ˜ ao 1 1 Instituto de F´ ısica ‘Gleb Wataghin’, Universidade Estadual de Campinas, CP 6165, 13083-970 Campinas SP, Brazil 2 Departamento de F´ ısica, Universidade Federal do Amazonas, 69077-000 Manaus AM, Brazil E-mail: coluci@ifi.unicamp.br Received 17 November 2004, in final form 12 January 2005 Published 1 March 2005 Online at stacks.iop.org/Nano/16/583 Abstract The motion of coupled oscillators based on multiwalled carbon nanotubes is studied using rigid-body dynamics simulations. The results show the existence of chaotic and regular behaviours for a given total energy, indicating the manifestation of chaos in nanoscaled mechanical systems based on carbon nanotube oscillators. Different regular motions are observed for different total energies, and they can be obtained by appropriately choosing the initial conditions. This possibility can allow the construction of multi-functional nano-devices based on multiwalled carbon nanotube oscillators. M This article features online multimedia enhancements 1. Introduction It has become common knowledge that multiwalled carbon nanotubes (MWNTs) [1] represented a breakthrough in nanotechnology [2]. New and exciting phenomena have been observed in these systems [3], including field emission [4], quantum conductance [5], constant-force nanosprings [6], as well as proposals for MWNT-based nano-devices [7]. High-resolution transmission electron microscopy (HRTEM) experiments involving MWNTs have demonstrated an ultra- low friction telescopic extension of MWNTs, opening up the possibility of building new kinds of nano-devices such as linear bearings [6] and nano-oscillators [7]. Analyzing a slightly modified configuration of the HRTEM experiments of Cumings and Zettl [6], Zheng and Jiang [7] have proposed an MWNT-based mechanical oscillator which could oscillate at gigahertz range. The oscillation mechanism is due to the excess of the van der Waals potential energy which leads to a restoring force acting on the MWNT core and causing its retraction to the equilibrium position [8]. Several studies involving double-walled carbon nanotubes have been carried out in order to investigate the operation of such nanotube-based devices [9–16]. An application of carbon nanotube oscillators as building blocks for nanoscale engines has been investigated by Kang and Hwang using molecular dynamics simulations [17]. They have analysed the integration of different nano-devices and their respective functionalities to simulate the operation of a nanoscale engine based on carbon nanotube oscillators. This approach creates the possibility of using integrated carbon nanostructures in the design of nano-engineering machines. The goals of the present work are to propose and study a modification of the carbon nanotube oscillator configuration [7] in order to allow the movement of more than one tube. This new configuration can be seen as two coupled carbon nanotube oscillators and represents a new building block type for nano-machines. We have demonstrated that chaotic and regular movements can appear in such a configuration. It is well known that oscillator based configurations, such as the Duffing oscillator and the double pendulum, can exhibit chaotic behaviours. The irregular behaviour of many physical systems has been the subject of intense experimental and theoretical investigations [18, 19]. Chaotic manifestations can appear in systems with different size scales, from the quantum domain (the behaviour of a hydrogen atom in an oscillating electric field [20–22]) to stellar dimensions with, for instance, the motion of a relativistic three-body self- gravitating system [23]. The system of two coupled carbon nanotube oscillators investigated in this work is an example of a nanoscaled configuration which can exhibit chaotic behaviour. 0957-4484/05/040583+07$30.00 © 2005 IOP Publishing Ltd Printed in the UK 583