Hydration Simulations of a Carbon Nanotube, immersed in Water, according to the 3-Attractor Water Model

MC simulations of a set of zigzag ((9,0)-(14,0)) and armchair ((6,6)-(10,10)) carbon nanotubes immersed in water have been carried out in an NpT-ensemble (512 water molecules, p=1 bar, T=298 K). Intermolecular interactions were described by BMW potential according to which, besides the well-known linear water dimer bifurcated and inverted water dimers are metastable. In all cases, it was found that there are large periodic fluctuations of water occupancy inside the nanotubes. Decrease in the size of the nanotube diameter leads to a significant destruction of the H-bond network, and to a bifucarted dimer population increase. Inverted dimer concentration relationship with the nanotube diameter is more complicated. Population maximum for inverted dimers occurs for diameters of 1011 Å. Water features different intermolecular structures not only inside carbon nanotubes but also in the outer first hydration shells. The amount of bifurcated and inverted dimers is significantly more important in the first hydration shell than in bulk water.