Papers by Keyword: Molecular Dynamic (MD)

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Authors: S.M. Kim, Hyun Kyu Kweon
Abstract: This study is about the underlying conjugation mechanism between carbon nanotube and biomolecule by molecular dynamics. In order to know about the conjugation mechanism between carbon nanotube and biomolecule, molecular dynamics simulation between carbon nanotube and water molecules was taken first and then molecular dynamics simulation between biomolecules and water molecules was taken. At simulation between carbon nanotube and water molecules, kinetic energy and potential energy became decreased with time and it means that the distance between carbon nanotube and water molecules becomes distant with time by van der Waals force and hydrophobic force. Simulation results between biomolecules and water molecules are also same as the results of carbon nanotube and water molecules simulation. From these two simulations, the conjugation mechanism between carbon nanotube and biomolecules can be predicted. Also, from simulation results between carbon nanotube and biomolecules, the distance between carbon nanotube and biomolecules becames close and it supports previous two simulation results. From these results, we can know that biomolecules enter into the carbon nanotube's cavity because of van der Waals force and hydrophobic force.
Authors: Dušan Račko
Abstract: In the Present Contribution the Atomistic Structure of the Polymer Melt at 300 K Is Simulated by Means of Molecular Dynamics. the Agreement with an Experimental Density Is Obtained with a Deviation Lower than 1%. the Free Volume Is Analyzed in 1,000 Structures and 6.5 X 108 Cubic Å of Molecular Space. a Model for the Free Volume Cavities Is Proposed. in the Model the Size and Number of the Cavities Can Be Scaled by Three Parameters: Probe Radius, Cavity Depth and Cavity Threshold Volume. the Experimental Values of the Nano-Sized Cavity Volumes as Well as Ortho-Positronium Lifetimes Are Obtained, as Compared to Models with Cylindrical and Spherical Geometry. a Typical Value of the Number Density of Free Volume Cavities at 0.001 Å-3 Is Obtained. the Cavities Have Typically Elongated Shape with a Side-to-Length Ratio 1:2.
Authors: Kausala Mylvaganam, Liang Chi Zhang
Abstract: This paper discusses the methods of promoting covalent bonds between polymer and carbon nanotubes to make high performance composites. Such methods involve attachment of chemical moieties (i.e. functional groups) to the sidewalls of carbon nanotubes, introduction of mechanical deformation on nanotubes, or generation of radicals on the polymer chains using free radical generators. The implementation of the latter method is demonstrated at both quantum mechanics and molecular dynamics levels.
Authors: Yu Mei Dai, Yu Jie Dai
Abstract: The molecular dynamic method and interface diffusion theory are used to simulate Ni/Al metal interface diffusion. One of the unit cells containing 576 Ni atoms and 128 Al atoms is chosen and computed under different temperatures (600K, 700K, 800K, 900K, 1000K, 1100K, 1200K, 1300K), respectively. We mainly analyze the position image of the interface diffusion atoms of Ni/Al interface reaction and the radial distribution function curve of the selected region, after the molecular dynamics program running 1200000 steps, under different temperatures, at initial diffusion time.
Authors: Kang Qi Fan, Chun Hui Xu, Feng Bo Chao
Abstract: There have been increasing research interests in the measurement of the mechanical properties of nanoscale materials by pressing a spherical tip into surfaces of the tested materials. To acquire a better understanding of this process, a model of adhesive contact between a spherical tip and a flat surface is developed by employing the Hamaker hypotheses and molecular dynamics (MD) method. With this model, the deformation characteristics of the tested surface are illustrated by the key snapshots of the deformed surface and the corresponding curves of pressure distribution. The results indicate that the contact can be formed before the tip impresses into the surface. Moreover, the variation of the adhesive force with the distance is recorded during the approach and separation processes, and the adhesion hysteresis is demonstrated by the force-distance curve. Additionally, the stepwise increase of the contact radius with a decrease in the distance is revealed and investigated.
Authors: Sen Wang, Zhi Hui Li, Xin Liu, Huan Zhang
Abstract: Oxygen diffusion in MgO stabilized zirconia has been studied by molecular dynamics simulation method with MOLDY software. The results illustrate that oxygen diffusion in MgO stabilized zirconia can be decided by temperature and amount of MgO. Both increase of amount of MgO and temperature in the system may promote the oxygen diffusion. Further increase in temperature is helpful to the oxide ions diffusion. There is always a maximum value of oxygen diffusion coefficient, which is represented by the slope of MSD curves, corresponding to a certain amount of MgO. In MgO stabilized zirconia, the most suitable doped amount of MgO exists in a range , which is decided by the working temperature of MgO stabilized zirconia.
Authors: Takashi Tokumasu
Abstract: The dissociation phenomena of H2 molecule on Pt(111) surface was simulated by Molecular Dynamics (MD) method and the effect of motion of the gas molecule or surface atoms on dissociation phenomena was analyzed in detail. The Embedded Atom Method (EAM) was used to model the interaction between an H2 molecule and Pt(111) surface. Using this potential, simulations of an H2 molecule impinging on a Pt(111) surface were performed and the characteristics of the collision were observed. Using MD data the dynamic dissociation probability were obtained and compared with the static dissociation probability to analyze the effect of atomic motion on dissociation phenomena.
Authors: Chen Dong
Abstract: The diffusion behaviors of Fe adatom on Fe nanoparticles with three different sizes have been explored by molecular dynamics (MD) simulation. The activation energies and pre-exponential factors are extracted from the Arrhenius relation. The MD simulation shows that the hopping, exchange and direct/indirect crossing mechanisms contribute to the diffusion of Fe adatom on Fe nanoparticles and the diffusion behaviors do not show a significant nanosize effect.
Authors: H. Ogawa, N. Sawaguchi, Fumihiro Wakai
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