Molecular dynamic of selectivity and permeation based on deformed carbon   nanotube
  Extensive molecular dynamics simulations of water permeation and ion selectivity of the single-walled carbon nanotubes with the radial deformation are presented . The simulated results indicate that there is a close relationship between the minor axis of deformed carbon nanotubes and the variety, density as well as the position of functional groups. The critical minor axis of different diameter carbon nanotubes exists, and the carbon nanotube whose minor axis is less than the critical minor axis owns the selectivity of chlorine and sodium ions. Meanwhile, compared with intrinsic carbon nanotubes, the deformed nanotubes have not obviously decreased the permeation of water. The analysis to the potential of mean force reveals that the selectivity and permeation of ions comes from the pass potential barrier of carbon nanotubes with various minor axises. Furthermore, our observations of modifying with functional groups may have significance for controlling the minor axis and improving the selectivity and permeation of ions, when it comes to some large nanotube in real manufacture. 
Xu Kui, Wang Qing-Song, Tan Bin, Chen Ming-Xuan, Miao Ling, Jiang   Jian-Jun
cond-mat.mes-hall