Simulating the process of water passing through carbon nanotube

Dr. Gerhard Hummer

Arm-chair type nanotube

http://mailhost.ccs.uky.edu/~ernst/carbontubes/structure.html

Water insert into the nanotube

www.ks.uiuc.edu/Training/Tutorials/science/nanotubes.pdb

Lannard-Jones potential

A. Waghe, J.C. Rasaiah and G. Hummer. J.Chem.Phys., 117,10789(2002).

G. Hummer, J.C. Rasalah & J.P.Noworyta. Nature,414,188(2001).

G. Hummer, J.C. Rasalah & J.P.Noworyta. Nature,414,188(2001).

-2.1kBT per water molecule, indepent of tube length

S. Vaitheeswaran,J.C.Rasaiah & G. Hummer. J. Chem. Phys.,121,7955(2004).

Temperature effect

S. Vaitheeswaran,J.C.Rasaiah & G. Hummer. J. Chem. Phys.,121,7955(2004).

Effect of external field

Thermodynamic properties for the modified tube in a uniform electric field E parallel to the

tube axis at T=298K

Conclusion

Hydrophobic channels can have significant water occupancy despite a reduction in the number of hydrogen bonds compared to the bulk fluid.Small changes in the nanotube-water interactions can lead to large changes in the water occupancy of the channel.Temperature and external field can improve the occupancy probabilities.

Water model

TIP3P

ModelDipole

moment

Dielectric

constant

Self diffusion, 10-5 cm2/s

Average configurational energy, k

J mol-1

Density

maximum,

°C

Expansion

coefficient,

10-4 °C-

1

TIP3P  2.35  82  5.19  -41.1  -13  9.2