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1.
Molecular dynamics simulation on mechanicalproperty of carbon nanotube torsional deformation 总被引:3,自引:0,他引:3
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In this paper torsional deformation of the carbon nanotubes is simulated by
molecular dynamics method. The Brenner potential is used to set up thesimulation
system. Simulation results show that the carbon nanotubes can bear larger torsional
deformation, for the armchair type (10,10) single wall carbon nanotubes, with a
yielding phenomenon taking place when the torsional angle is up to
63$^{\circ}$(1.1rad). The influence of carbon nanotube helicity in torsional
deformation is very small. The shear modulus of single wall carbon nanotubes should
be several hundred GPa, not 1\,GPa as others reports. 相似文献
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The behavior of nano-confined water is expected to be fundamentally different from the behavior of bulk water.At the nanoscale,it is still unclear whether water flows more easily along the convergent direction or the divergent one,and whether a hourglass shape is more convenient than a funnel shape for water molecules to pass through a nanotube.Here,we present an approach to explore these questions by changing the deformation position of a carbon nanotube.The results of our molecular dynamics simulation indicate that the water flux through the nanotube changes significantly when the deformation position moves away from the middle region of the tube.Different from the macroscopic level,we find water flux asymmetry(water flows more easily along the convergent direction than along the divergent one),which plays a key role in a nano water pump driven by a ratchet-like mechanism.We explore the mechanism and calculate the water flux by means of the Fokker-Planck equation and find that our theoretical results are well consistent with the simulation results.Furthermore,the simulation results demonstrate that the effect of deformation location on the water flux will be reduced when the diameter of the nanochannel increases.These findings are helpful for devising water transporters or filters based on carbon nanotubes and understanding the molecular mechanism of biological channels. 相似文献
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采用拉伸分子动力学方法研究了单壁碳纳米管(8, 8)在室温下从硅基板上被剥离的过程.当碳纳米管(CNT)在硅基底上被剥离时, 剥离距离和理想弹簧所测平均剥离力之间呈现一定规律的关系曲线,并出现了较大的正、负峰值. 比较了不同剥离速度下的平均剥离力,并拟合了其峰值与速度的关系. 拉伸分子动力学模拟结果显示,所需剥离力的最大值与速度之间呈现一定的线性关系, 模拟结果同生物物理学上类似的剥离实验结果符合较好,但相比于高分子, CNT和硅(Si)组成的界面吸附性能更强.讨论了碳纳米管长度、 半径及缺陷对剥离过程的影响,研究表明:所需最大的剥离力与CNT的长度无关, 但随CNT半径的增加,需要的最大剥离力线性增加; 5-7-7-5缺陷对剥离力最大值影响较小,而半径变化缺陷会削减最大剥离力. 在原子尺度对未来的试验进行了理论预测,为碳纳米管在硅微电子工业中的应用提供了理论基础. 相似文献
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采用改进的经验键序作用势描述碳原子间的相互作用,应用分子动力学方法和Green-Kubo函数计算了碳纳米管的热导率.在模拟中,使用了重叠计算的方法来计算热流相关函数,大大减少了模拟步数.计算结果表明,碳纳米管的热导率以原子间作用力相互做功所引起的热流形式为主;热导率的值随着直径的增加而减小;在室温下,热导率的值随着温度的增加而增加,达到室温后逐渐收敛于定值.计算的单壁碳纳米管热导率在1000W/mK至4000W/mK之间,计算结果与实验结果基本符合.
关键词:
分子动力学
碳纳米管
热导率 相似文献
6.
本文采用分子动力学模拟方法研究了Si表面间单壁水平碳纳米管束SWCNT (10,10)的变形和摩擦特性.系统在弛豫平衡后,首先对碳纳米管束施加压力至碳纳米管或Si表面结构破坏.之后在无压力和高压力两种情况下使上表面沿水平方向做剪切运动以研究碳纳米管束的摩擦特性.结果表明,由于碳纳米管的柔韧性,碳纳米管束在加载过程中出现明显变形,但直至3.8 GPa高压下并无结构破坏.系统无压力时SWCNT (10,10)在原地轻微随机滚动,压力为3.8 GPa时,碳纳米管束出现了整体的轻微滑动,同时伴随无规律的轻微滚动,
关键词:
碳纳米管束
摩擦
分子动力学模拟 相似文献
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In this paper we present some simulation results about the behaviour
of water molecules inside a single wall carbon nanotube (SWNT). We
find that the confinement of water in an SWNT can induce a wave-like
pattern distribution along the channel axis, similar phenomena are
also observed in biological water channels. Carbon nanotubes(CNTs)
can serve as simple nonpolar water channels. Molecular transport
through narrow CNTs is highly collective because of tight hydrogen
bonds in the protective environment of the pore. The hydrogen bond
net is important for proton and other signal transports. The average
dipoles of water molecules inside CNTs (7,7), (8,8) and (9,9) are
discussed in detail. Simulation results indicate that the states of
dipole are affected by the diameter of SWNT. The number of hydrogen
bonds, the water--water interaction and water--CNT interaction are
also studied in this paper. 相似文献
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采用分子动力学模拟方法, 研究了填充在(8,8)单壁碳纳米管内的Au纳米线的结构和热稳定性. 研究表明, 经高温退火至室温, Au在碳纳米管内能生成多样而稳定的结构上明显区别于自由状态Au纳米线的壳层螺旋结构Au纳米线, 其螺旋结构会随着温度的变化而转变. 束缚在碳纳米管内的壳层螺旋结构Au纳米线有非常好的热稳定性, 稳定温度高于块体Au晶体的熔化温度.
关键词:
纳米线
碳纳米管
热稳定性
分子动力学模拟 相似文献
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Molecular dynamics (MD) simulations were performed to provide an insight about the molecule distribution and thermophysical properties of n-heptacosane confined in the (25, 25) single-walled carbon nanotube (CNT). The results show that an orderly distribution of n-heptacosane molecules along the CNT inner wall is clearly observed. Meanwhile, n-heptacosane confined in CNT exhibits an increased self-diffusion coefficient, a decreased melting point and an enhanced thermal conductivity, compared to the bulk. The simulations reveal that MD is an effective and convenient method to understand the variation characteristics of alkane-based phase change materials confined in CNT on molecular and atomic scale. 相似文献
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通过分子动力学方法模拟了在碳纳米管内填充一定数目的半导体元素硅形成碳纳米管-硅纳米线复合结构的过程,并采用Lindemann指数研究了这种复合结构的热稳定性.计算结果表明,当考虑碳纳米管和硅纳米线轴向方向的周期性边界条件之后,在C(13,0)和C (14,0)碳纳米管内能够形成亚稳结构的硅纳米线Si16NW和Si20NW,从而获得一种碳纳米管-硅纳米线的新型复合结构.通过计算这种复合结构的Lindemann指数,可以看到由于碳纳米管的保护作用,碳纳米管包裹的硅纳
关键词:
复合结构
纳米线
碳纳米管
分子动力学 相似文献
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采用TLHT势和经典分子动力学方法研究了稀有气体原子(He,Ne,Ar,Kr,Xe)进入带缺陷的单壁纳米碳管(SWCNT)的动力学过程,计算出了稀有气体原子分别从管壁和管口入射时,它们能封装在SWCNT中的能量阈值Ek0,并与理想结构情形做了比较.结果表明:随着管壁缺陷半径r的增加,Ek0减小;当r<4.5 ?时,给定合适的初始动能,稀有气体原子能封装在纳米碳管中;而r=4.5 ?时,稀有气体原子不能封装在碳管中,且此时缺陷对Ar,Kr和Xe的输运特性有很大影响.
关键词:
纳米碳管
缺陷
稀有气体原子
分子动力学模拟 相似文献
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Seifollah Jalili Arezou Jaberi Mohammad Ghasem Mahjani Majid Jafarian 《Molecular physics》2013,111(6):361-368
Utilising molecular dynamics simulations, the hydrogen molecules adsorption isotherms of the (8,?0) palladium decorated single-walled carbon nanotube (SWNT) were obtained. The hydrogen adsorption was studied on the external, interstial and internal surfaces of the SWNT bundle at several temperatures ranging from 77 to 400?K. The results were compared with the bare single-walled carbon nanotube bundle under the same conditions. The decorated carbon nanotube bundle hydrogen adsorption was significantly higher than that of the bare one. The hydrogen desorption and readsorption were studied using temperature as the readsorption/desorption variable. The rate constants were calculated for the hydrogen desorption at different temperatures. The calculated decorated SWNT bundle hydrogen desorption activation energy was higher than that for the bare SWNT bundle. The calculated activation energies for the hydrogen desorption in both nanotube bundles specified the temperature dependency of hydrogen desorption. 相似文献
18.
Using a water-confined carbon nanotube to probe electricity of sequential charged segments of macromolecules
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The detection of macromolecular conformation is particularly important in many physical and biological applications. Here we theoretically explore a method for achieving this detection by probing the electricity of sequential charged segments of macromolecules. Our analysis is based on molecular dynamics simulations, and we investigate a single file of water molecules confined in a half-capped single-walled carbon nanotube (SWCNT) with an external electric charge of +e or ?e (e is the elementary charge). The charge is located in the vicinity of the cap of the SWCNT and along the centerline of the SWCNT. We reveal the picosecond timescale for the re-orientation (namely, from one unidirectional direction to the other) of the water molecules in response to a switch in the charge signal, ?e → +e or +e → ?e. Our results are well understood by taking into account the electrical interactions between the water molecules and between the water molecules and the external charge. Because such signals of re-orientations can be magnified and transported according to Tu et al. [2009 Proc. Natl. Acad. Sci. USA 106 18120], it becomes possible to record fingerprints of electric signals arising from sequential charged segments of a macromolecule, which are expected to be useful for recognizing the conformations of some particular macromolecules. 相似文献
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纳米尺度金属Ag以其独特的导电和导热性,广泛应用于微电子、光电子学、催化等领域,特别是在纳米微电极和纳米器件方面的应用.本文采用分子动力学方法模拟了不同晶粒尺寸下多晶银纳米线的拉伸变形行为,详细分析了晶粒尺寸对多晶银纳米线弹性模量、屈服强度、塑性变形机理的影响.发现当晶粒尺寸小于13.49 nm时,多晶Ag纳米线呈现软化现象,出现反Hall-Petch关系,此时的塑性变形机理主要以晶界滑移、晶粒转动为主,变形后期形成五重孪晶;当晶粒尺寸大于13.49 nm时,塑性变形以位错滑移为主,变形后期产生大量的孪晶组织. 相似文献