Quasi one dimensional $^4$He inside carbon nanotubes

TL;DR

This study uses diffusion Monte Carlo to compare $^4$He behavior inside narrow carbon nanotubes and in strictly one-dimensional systems, revealing increased binding energy and phase transition characteristics.

Contribution

It provides the first detailed quantum Monte Carlo comparison of $^4$He in nanotubes versus 1D systems, highlighting differences in energetic and structural properties.

Findings

Binding energy inside nanotubes is three times larger than on graphite.

$^4$He in nanotubes exhibits 1D quantum fluid behavior at low densities.

Both systems undergo a liquid-solid phase transition at high densities.

Abstract

We report results of diffusion Monte Carlo calculations for both $^4$He absorbed in a narrow single walled carbon nanotube (R = 3.42 \AA) and strictly one dimensional $^4$He. Inside the tube, the binding energy of liquid $^4$He is approximately three times larger than on planar graphite. At low linear densities, $^4$He 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 quasi-continuous liquid-solid phase transition is observed in both cases.