Structure and dynamics of confined water inside narrow carbon nanotubes.
We have performed atomistic molecular dynamics (MD) simulations of water molecules inside narrow, open-ended carbon nanotubes placed in a bath of water molecules. The radius of the tube is such that only a single file of water molecules is allowed inside the tube. The confined water molecules are shown to be positionally ordered even at a temperature of 300 K. The calculated mean-square displacement (MSD) of the confined water molecules reveals that initially the water molecules undergo ballistic motion that crosses over to normal (Fickian) diffusion at longer times. We also develop a random-walk model in 1D for the motion of a cluster of water molecules inside the nanotube. The agreement of the MSD calculated from the MD simulation and from the 1 D random-walk model establishes the occurrence of normal diffusion of water molecules even in a tube where single-file diffusion is expected.
Mukherjee
Biswaroop
B
Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore, India.
Maiti
Prabal K
PK
Dasgupta
Chandan
C
Sood
A K
AK
D003198:Computer Simulation; D003460:Crystallization / Q000379:methods*; D004058:Diffusion; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D036103:Nanotechnology / Q000379:methods*; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D016062:Porosity; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
D046911:Macromolecular Substances; D037742:Nanotubes, Carbon; D014867:Water