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Molecular Dynamics Simulation Of The Microscopic Characteristics Of Water Molecules Confined In Carbon Nanotubes

Posted on:2016-07-04Degree:MasterType:Thesis
Country:ChinaCandidate:H F YangFull Text:PDF
GTID:2181330467492340Subject:Condensed matter physics
Abstract/Summary:PDF Full Text Request
In this paper, the structural and dynamic behaviors of water confined in carbon nanotubeswere simulated by using molecular dynamics method. The impacts of water moleculemodels(SPC/E、 TIP4P、 TIPS2), temperature and pore width on the structure and theaggregation characteristics for water were investigated, the effects of electric dipole momentand electric quadrupole moment on the diffusion coefficient and on the structure of water wereexplored. The results indicate that the aggregation behavior of bulk water does not showsignificant differences due to the discrepancy of the three different models, however, thestructure of water in carbon nanotube has shown a relatively significant difference. The resultsshow that the electric dipole moment plays a major role in the diffusion coefficient, while theelectric quadrupole moment plays a leading role in the structure of water. In the same widthpores, as the temperature increases, the degree of ordering of water gradually decreases. Theresults indicate that, when the diameter of the carbon nanotube is small, most of the watermolecules gather in the vicinity of the central axis of the tube, while in the larger width pore,the water molecules are mostly gathered in the vicinity of the wall. Looking along differentdirections, water molecules in different width pores have exhibited different structures, Lookingperpendicular to the pores, water molecules form a single chain in SWCNT(6,6),twined doublechains in SWCNT(7,7), Looking parallel to the pores, quadrangular stacks formed inSWCNT(8,8).In order to explore the translational motion of water in carbon nanotubes within a shorttime, several successive simulation snapshots of32water molecules in SWCNT(9,9) at300Kwere intercepted. We found that the water molecules formed clusters, and the clusters slidingperiodically with small friction. Velocity autocorrelation function is calculation so as to explore detailed behavior of motion for the clusters. The results show that velocity autocorrelationfunction has an oscillating feature. However, due to the correlations of the velocities can bedestroyed by the collisions between the water molecules and between the water molecules andthe carbon atoms, so the oscillation decays very quickly.
Keywords/Search Tags:molecular dynamics simulation, structure of water, diffusion, electric dipolemoment, electric quadrupole moment
PDF Full Text Request
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