Quasi-one-dimensional 4He inside carbon nanotubes

We report results of diffusion Monte Carlo calculations for both He-4 absorbed in a narrow single walled carbon nanotube (R=3.42 Angstrom) and strictly one-dimensional He-4. inside the tube, the binding energy of liquid He-4 is approximately three times larger than on planar graphite. At low Linear densities, He-4 in a nanotube is an experimental realization of a one-dimensional quantum fluid. However, when the density increases the structural and energetic properties of both systems differ. At high density, a quasicontinuous liquid-solid phase transition is observed in both cases.