Dilation-induced phases of gases absorbed within a bundle of carbon nanotubes

A study is presented of the effects of gas (especially H-2) absorption with in the interstitial channels of a bundle of carbon nanotubes. The ground st ate of the system is determined by minimizing the total energy, which inclu des the molecules' interaction with the tubes, the intertube interaction, a nd the molecules' mutual interaction (which is screened by the tubes). The consequences of swelling include a reduced threshold pressure for gas uptak e and a 2.7% increase in the tubes' breathing mode frequency.