碳纳米豆荚内C60分子的振荡行为

摘要

Based on molecular dynamics simulation,combined with the AIREBO potential and Lennard Jones potential,the oscillation of C60 molecule in carbon nanopeapods were studied,with consideration on the influence of tube length,diameter and axial pre-stress.Results showed that the C60 molecule oscillates periodically along the axial direction of carbon nanotubes due to the long-range van der Waals interaction and sliding friction force.The increase of both tube length and diameter leads to a monotonously linear decrease of the oscillation frequency of the C60 molecule,and there exists a lower critical diameter where an oscillation can oc-cur.Due to the effect of the van der Waals interaction,when the tube diameter is larger,the oscillation track of C60 molecule deviates from the tube axis and becomes close to one side tube wall.Axial pre-stress also has a strong influence on the oscillation:the oscillation frequency of C60 molecule decreases linearly with the increase of tensile pre-stress,while decays in a piecewise linear mode when the axial compressive pre-stress rises.A sharp decline happens after a critical compressive pre-stress.These results may pro-vide helpful guidelines and reference to future development of high-frequency oscillation components based on carbon nanopeapods.%近年来C60分子与碳纳米豆荚组成的碳纳米豆荚的高频振荡行为受到了学术界的广泛关注,并有望在振荡器元器件等领域获得潜在应用.本工作基于分子动力学模拟方法,结合碳-碳多体势函数和Lennard Jones对势函数,对碳纳米豆荚中C60分子的振荡行为进行了模拟研究,并分别讨论了碳纳米管长度、直径及轴向预应力对碳纳米豆荚振荡性能的影响.研究结果表明,C60分子受到其与碳管间的长程范德华力及滑动摩擦力的作用,沿碳纳米管轴线方向做周期性往复振荡运动.碳纳米管长度和直径的增加均会导致C60分子振荡频率单调减小,且存在一个振荡发生的临界直径下限值;由于范德华力相互作用的影响,当直径较大时,C60分子将发生偏心振动,振荡轨迹偏离碳管轴线而贴近一侧管壁.轴向预应力对C60分子的振荡行为也有明显影响:随轴向拉伸预应力的增加,C60分子振荡频率单调减小;当轴向预应力为压应力时,C60分子振荡频率的衰减为分段线性模式,在越过临界压应力后急剧下降.这些研究结果将对基于碳纳米豆荚的高频振荡元器件的开发提供有益的指导与参考.