Gas condensation within a bundle of carbon nanotubes - effects of   screening
  We study the low temperature phase behavior of hydrogen within a bundle of carbon nanotubes. Because the carbon environment weakens the attraction between molecules within the same interstitial channel (IC), the ground state of the one-dimensional (1D) system is an uncondensed gas. When the screened attractive interaction between molecules in adjacent ICs is taken into account, the hydrogen ground state is a quasi-1D liquid. The critical temperature of this system is estimated. 
M.K. Kostov, J.C. Lewis and M.W. Cole