Water ice in nanotubes
Inspired by the article of Bai, Wang and Zeng "Multiwalled ice helixes and ice nanotubes", PNAS 103:52 (26 DEC 2006)
If you put water in a nanotube under different pressures and freeze, then it can take an interesting shapes.
If the pressure is not very high eighth-sided tube with a single chain of water along the axis may be formed.file
At a higher pressure twelve-sided helix forms around a four-sided tube. It is interesting that parameters of the water helix are close to the parameters of the DNA B-form.file
Conditions of simulation: 2 ns of molecular dynamics at 250.15 K.