The study on diffusion behaviors of water molecules withincarbon nanocoils by molecular dynamics simulation

• Main Authors: Ming-Chang Chen, 陳明璋
• Other Authors: Shin-Pon Ju
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/97382347798136220610

碩士 === 國立中山大學 === 機械與機電工程學系研究所 === 100 === In this study, molecular dynamics (MD) simulations was employed to investigate (5,5), (10,10) single-walled nanocoils and (5,5)@(10,10) double-walled carbon nanocoils. The study can be arranged into two parts： In part I: Investigate the mechanical properties of (5,5), (10,10) single-walled nanocoils and (5,5)@(10,10) double-walled carbon nanocoils. The second reactive empirical bond order (REBO) potential was employed to model the interaction between carbon atoms. The contours of atomic slip vector and sequential slip vector were used to investigate the structural variations at different strains during the tension process. The yielding stress, maximum tensile strength, and Young’s modulus were determined from the tensile stress-strain profiles. The results show that the nanocoils have superelastic characteristics to the carbon nanotube in the same tube diameter. In part II: Investigate the diffusion behavior of water molecules confined inside narrow (5,5) and (10,10) carbon nanocoils under different tensile strains. The condensed-phase optimized molecular potentials for atomistic simulation studies (COMPASS) potential was employed to model the interaction between carbon-carbon atoms，carbon atoms-water molecules and water-water molecules. To analysis the kinetic behavior of water molecules in two carbon nanocoils, the diffusion coefficients, square displacement (SD) and mean square displacement (MSD) of water molecules were calculated. The results show that diffusion coefficient of water will increase with the strains of carbon nanocoils. However, the diffusion coefficient has a significant decrease in a large strain due to the structural deformation of carbon nanocoils. The diffusion behaviors of water inside the (5,5) and (10,10) carbon nanotubes were also investigated to compare the results in (5,5) and (10,10) carbon nanotubes. Our results indicate that two carbon nanocoils have a lower diffusion coefficient of water than that of carbon nanotubes because the geometry of carbon nanocoil is easily to block up the diffusion of water molecules.