Interaction of HF, HBr, HCl and HI Molecules with Carbon Nanotubes.

The present work applies the density functional theory (DFT) to study the interactions between armchair (n,n) single walled carbon nanotubes (SWCNTs) and hydrogen halides confined along the nanotube axis and perpendicular to it. Calculations are performed using the CAM-B3LYP functional. According to the hydrogen halides orientation and the internal diameter of CNTs hollow space, HF, HCl, HBr and HI behave differently. The nanoconfinement alters the charge distribution and the dipolar moment. The encapsulated hydrogen fluoride (HF) molecule is stable along and perpendicular to the nanotubes (5,5) and (6,6) axis. The hydrogen chloride (HCl), hydrogen bromide (HBr) and hydrogen iodide (HI) form stable systems inside the nanotube (6,6) only at the perpendicular orientation. In addition, other phenomena are observed such as leaving the nanotube or decreasing the bond length of the molecule and even the creation of covalent bind between the guest molecule and the host nanotube.