中文摘要：

采用非平衡分子动力学方法研究了有限长度、开口单壁碳纳米管中氦分子的输运过程.结果表明氦分子在小管径碳纳米管中主要以超扩散方式运动.当碳纳米管直径大于某一阈值时发生从超扩散向弹道输运方式的转变,而随着管径的继续增大,分子输运重新以超扩散的方式进行.这种转变与纳米管端口效应有密切的联系.当碳纳米管内部分子通过弹道方式高速运动时,这种运动在端口处由于端部势垒的影响而被抑制,造成端部阻塞现象,其本质是受端部势垒和碳纳米管管径共同影响的结果.

英文摘要：

The transport of helium molecules in open and finite-length single-walled carbon nanotubes was studied using non-equilibrium molecular dynamics simulations.We observed that helium molecules were transported through nanotubes with the high mobility characterized by superdiffusion.A transition from superdiffusion to near-ballistic motion occurs when the diameter is larger than a threshold value,and then the transport is again dominated by the superdiffusion.This change is closely related to nanotube ends.Simulations show that molecules are transported rapidly in the nanotubes via ballistic motion,which,however,is dispersed by the potential barrier at the ends of the nanotubes.This blocking effect is jointly determined by the potential barrier and the nanotube diameter.