Quasi-One-Dimensional Solid Lattice and Liquid Hydrogen in Single-Walled Carbon Nanotubes

We study the H₂ molecules confined in single-walled carbon nanotubes by using molecular dynamics simulations and ab initio calculations. It is found that the H₂ molecules at zero-temperature with low density tend to condense. When the linear density of the H₂ molecules in the tube increases, various quasi-one-dimensional solid lattices can be observed at low temperature. When the lattices are heated above room temperature, molecular H₂ liquids with different density can be observed. The quenching behaviour of the H₂ fluids is also examined.