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arXiv 0904.0735cond-mat.mes-hall
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基于碳纳米管的纳机电系统中的耗散和涨落

Dissipation and fluctuations in nanoelectromechanical systems based on carbon nanotubes

I. V. Lebedeva, A. A. Knizhnik, A. M. Popov, Yu. E. Lozovik, B. V. Potapkin

摘要:

以千兆赫振荡器为例,研究了纳米管纳米机电系统的摩擦学特性。利用分子动力学方法计算了纳米管振荡器的品质因数(Q因子),定量分析了各种因素对纳米管NEMS摩擦学性能的影响.我们证明了纳米管壁的可折叠性可以增加耗散率,而壁端结构和纳米管长度不影响Q因子。结果表明,耗散率取决于壁间距离和外壁的固定方式,并且在具有大壁间距离的纳米管的固定不良的情况下是显著的。缺陷被发现强烈降低的Q-因子,由于低频振动模式的激发。静摩擦力和能量耗散率之间没有普遍的相关性。我们提出了一个解释所获得的结果的基础上的经典理论的振动平移松弛。通过分子动力学模拟揭示了吉赫振荡器中的热力学涨落,并在涨落耗散定理的框架下进行了分析。在此基础上讨论了设计具有理想Q值的NEMS的可能性及其应用。

英文摘要:

Tribological characteristics of nanotube-based nanoelectromechanical systems (NEMS) exemplified by a gigahertz oscillator are studied. Various factors that influence the tribological properties of the nanotube-based NEMS are quantitatively analyzed with the use of molecular dynamics calculations of the quality factor (Q-factor) of the gigahertz oscillator. We demonstrate that commensurability of the nanotube walls can increase the dissipation rate, while the structure of the wall ends and the nanotube length do not influence the Q-factor. It is shown that the dissipation rate depends on the interwall distance and the way of fixation of the outer wall and is significant in the case of a poor fixation for the nanotubes with a large interwall distance. Defects are found to strongly decrease the Q-factor due to the excitation of low-frequency vibrational modes. No universal correlation between the static friction forces and the energy dissipation rate is established. We propose an explanation of the obtained results on the basis of the classical theory of vibrational-translational relaxation. Significant thermodynamics fluctuations are revealed in the gigahertz oscillator by molecular dynamics simulations and analyzed in the framework of the fluctuation-dissipation theorem. Possibility of designing the NEMS with a desirable Q-factor and their applications are discussed on the basis of the above results.

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