Temperature effects on the static and dynamic properties of liquid water inside nanotubes
Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, B5 Campus Nord, 08034 Barcelona, Catalonia, Spain. Physical Review E
(Impact Factor: 2.29).
09/2001; 64(2 Pt 1):021504. DOI: 10.1103/PhysRevE.64.021504
We report a molecular dynamics simulation study of the behavior of liquid water adsorbed in carbon nanotubes under different thermodynamic conditions. A flexible simple point charged potential has been employed to model internal and intermolecular water interactions. Water-carbon forces are modeled with a Lennard-Jones-type potential. We have studied three types of tubes with effective radii ranging from 4.1 to 6.8 A and three temperatures, from 298 to 500 K for a fixed density of 1 g/cm(3). Structure of each thermodynamic state is analyzed through the characterization of the hydrogen-bond network. Time-dependent properties such as the diffusive behavior and molecular vibrational spectra are also considered. We observe the gradual destruction of the hydrogen-bond network together with faster diffusive regimes as temperature increases. A vibrational mode absent in bulk unconstrained water appears in the power spectra obtained from hydrogen velocity autocorrelation functions for all thermodynamic states. That frequency mode should be attributed to confinement effects.
Available from: X. Chen
- "Therefore, in order to understand the above experimental results, theoretical and numerical studies are necessary. Molecular dynamics (MD) simulations have been carried out for studying the transport behaviours of molecules inside CNTs     . For instance, Hummer et al.  immersed a very short (6,6) CNT (with the length of about 1.3 nm and with both ends open) in a reservoir with 1000 water molecules, and reported that such an initially empty SWCNT can be filled instantaneously by surrounding water molecules under ambient conditions. "
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ABSTRACT: The mechanisms of pressure-driven water infiltration into single walled carbon nanotubes are explored using molecular dynamics simulations. Both quasi-static and dynamic loading conditions are investigated, and the influence of tube size is examined. Under quasi-static loading, the water molecules flow into the tube via surface diffusion at a low pressure and when the external pressure reaches a critical value, the infiltrated water flux can sharply increase to a steady state. Upon dynamic loading, the nominal infiltration length per unit external work is employed to measure the comprehensive effect of the loading rate. It is found that such factor is larger (i.e. infiltration is easier) at a lower loading rate and a larger tube size, which is closely related with the interactions between water molecules and nanotube wall atoms.
Molecular Simulation 09/2008; 34(10). DOI:10.1080/08927020802175225 · 1.13 Impact Factor
Available from: illinois.edu
- "However, the wall interactions in a polar pore are not negligible, as they appear to be in a hydrophobic pore. Simulations on carbon nanotubes  and hydrophobic pores   show that as the diameter of the pore is decreased below 20 Å, the average density of water decreases due to increasing frequency of transition to the vapor phase. At the same time, the diffusion coefficient increases—by as much as 3-fold in the narrowest channels to have significant water density. "
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ABSTRACT: Proton transfer and transport in water, gramicidin and some selected channels and bioenergetic proteins are reviewed. An attempt is made to draw some conclusions about how Nature designs long distance, proton transport functionality. The prevalence of water rather than amino acid hydrogen bonded chains is noted, and the possible benefits of waters as the major component are discussed qualitatively.
Biochimica et Biophysica Acta 09/2006; 1757(8):886-912. DOI:10.1016/j.bbabio.2006.06.017 · 4.66 Impact Factor
Nature 01/2001; 414:156-159. DOI:10.1038/414156a0 · 41.46 Impact Factor
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