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Modelling of nanooscillators

Roman I. Hrytskiv ,  Ivan M. Bolesta 

Ivan Franko National university of Lviv (LNU), Lviv 79017, Ukraine

Abstract

For last decades carbon nanotubes (CNT’s) are intensively studied due to their unique structure and wide range of potential applications. Recent experiments have shown that CNT’s can serve as elements of electromechanical systems such as nanoengines, nanooscillators, nanoresistors, nanotermometers and nanoactuators. Some of these devices have already laboratory prototypes. Furthermore, such systems will form a basis for future development of nanomechanics.

Nanooscillators are systems constituted by a pair of CNT’s put into each other, able to move periodically when not in equilibrium state. Such systems are studied mainly by means of computer simulations.

In presented work nanooscillators were investigated using molecular dynamics. Covalent interactions between carbon atoms inside a CNT were described by Tersoff potential while interactions of particles in the different tubes were modeled using Lennard-Jones potential.

Various systems formed by tubes with different geometry and with different initial conditions (such as temperature) were studied. Corresponding time dependences of frequency, amplitude and other characteristics obtained. In particular, the oscillator consisting of (9, 0) and (18, 0) tubes both of length 21 Å was considered. For this oscillator sustained oscillations were observed. The frequency has increased from 118 GHz at the beginning of the simulation up to 120 GHz in the end (the simulation was run for 1 ns time). The oscillations were found to be damped: amplitude has decreased for about 2.5% from the initial value after 1 ns. Periodical changes in the amplitude were discovered, which we assume to result from superposition of oscillator vibrations and longitudinal vibrations of inner and outer tubes. These vibrations of tubes are induced by Van der Waals forces acting during oscillations. The frequency of tubes oscillations was found to be two times higher than main oscillator frequency. This proves abovementioned assumption.

 

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Presentation: Poster at E-MRS Fall Meeting 2008, Symposium G, by Roman I. Hrytskiv
See On-line Journal of E-MRS Fall Meeting 2008

Submitted: 2008-05-12 10:12
Revised:   2009-06-07 00:48