Diffusion processes in a poly-crystalline zeolitic material: A molecular dynamics study

2018 ◽  
Vol 149 (6) ◽  
pp. 064702 ◽  
Author(s):  
Angela Mary Thomas ◽  
Yashonath Subramanian
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Processes ◽  
Zeolitic Material

Molecular Diffusion Processes in Crystalline Microporous Materials

1998 ◽  
Vol 527 ◽  
Author(s):  
G. Sastre ◽  
A. Corma ◽  
C. R. A. Catlow
Keyword(s):  
Molecular Dynamics ◽  
Chemical Composition ◽  
Diffusion Coefficients ◽  
Molecular Diffusion ◽  
Diffusion Processes ◽  
Diffusion Path ◽  
Microporous Structure ◽  
Microporous Material ◽  
Para Xylene ◽  
Channel Systems

ABSTRACTAtomistic Molecular Dynamics are used to simulate diffusion of hydrocarbons inside the microporous structure of siliceous zeolite CIT-I, with chemical composition SiO2. CIT-1 is a crystalline microporous material containing channels formed by rings containing 12 and 10 Si atoms (Figure 1). The dimensions of these two channel systems are sufficient to cause substantial differences in the diffusion of para-xylene and ortho-xylene. Diffusion coefficients as a function of loading of each isomer, and activation energies have been calculated from the simulations. The effect of the isomer size in the diffusion path is also analysed.

Study on Diffusion Processes of Water and Proton in PEM Using Molecular Dynamics Simulation

2011 ◽  
Vol 704-705 ◽  
pp. 1266-1272 ◽  
Author(s):  
Lei Chen ◽  
Wen Quan Tao
Keyword(s):  
Experimental Data ◽  
Molecular Dynamics ◽  
Water Content ◽  
Diffusion Processes ◽  
Calculation Model ◽  
Dynamics Simulation ◽  
Water Molecules ◽  
Hydrogen Ions ◽  
Model Cell ◽  
Dynamics Calculation

In this paper a molecular dynamics calculation model for the Nafion 117 membrane is constructed by Materials Studio (MS) software platform to study its micro-structure and transport properties. Based on the calculation model, cell structures of different water content of Nafion 117 membrane are obtained and the predicted density values of simulated cell are in good agreement with experimental data. Meanwhile, the diffusion processes of water molecules and hydrogen ions in the membrane are studied, respectively. The predicted diffusion coefficients of both water molecules and hydrogen ions increase with the water content, which agrees well with the variation trend of experimental data. The reasons for the deviation between numerical results and the experiment values in literature are analyzed.

Molecular Dynamics Simulation of Self-Diffusion Processes in Titanium in Bulk Material, on Grain Junctions and on Surface

2014 ◽  
Vol 118 (33) ◽  
pp. 6685-6691 ◽  
Author(s):  
Gennady B. Sushko ◽  
Alexey V. Verkhovtsev ◽  
Alexander V. Yakubovich ◽  
Stefan Schramm ◽  
Andrey V. Solov’yov
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Diffusion Processes ◽  
Bulk Material ◽  
Dynamics Simulation ◽  
Self Diffusion

Study of the Reactive Dynamics of Nanometric Metallic Multilayers Using Molecular Dynamics : The Al-Ni System

2012 ◽  
Vol 323-325 ◽  
pp. 89-94
Author(s):  
A. Linde ◽  
Olivier Politano ◽  
F. Baras
Keyword(s):  
Molecular Dynamics ◽  
Solid State ◽  
Solid State Reaction ◽  
Diffusion Processes ◽  
Layer By Layer ◽  
Fixed Temperature ◽  
Embedded Atom ◽  
Specific Geometry ◽  
Reactive Dynamics ◽  
Embedded Atom Method Potential

A molecular dynamics study of a layered Ni-Al-Ni system is developed using an embedded atom method potential. The specific geometry is designed to model a Ni-Al nanometric metallic multilayer. The system is initially thermalized at the fixed temperature of 600 K. We first observe the interdiffusion of Ni and Al at the interfaces, which is followed by the spontaneous phase formation of B2-NiAl in the Al layer. The solid-state reaction is associated with a rapid system's heating which further enhances the diffusion processes. NiAl phase is organized in small regions separated by grain boundaries. This study confirms the hypothesis of a layer-by-layer development of the new phase. For longer times, the temperature is notably higher (> 1000 K) and the system may partly lose some its B2-NiAl microstructure in favor of the formation of Ni3Al in L12 configuration. This work shows the spontaneous development of a real exothermic solid-state reaction in metallic nanosystems mostly constituted by interfaces.

ADSORPTION AND DIFFUSION PROCESSES OF POLYETHYLENE ON SILICON (111) SURFACE STUDIED BY MOLECULAR DYNAMICS SIMULATION

2011 ◽  
Vol 10 (04) ◽  
pp. 411-421 ◽  
Author(s):  
DAN MU ◽  
YI-HAN ZHOU
Keyword(s):  
Molecular Dynamics ◽  
Adsorption Energy ◽  
Diffusion Processes ◽  
Dynamic Properties ◽  
Relative Dielectric Constant ◽  
Hydrophobic Surface ◽  
Degree Of Polymerization ◽  
Dynamics Simulation ◽  
Chain Lengths ◽  
And Diffusion

The adsorption of polyethylene with different chain lengths on a silicon (111) surface is studied via molecular dynamics simulations. The relative dielectric constant is selected to be 1 and 78.0 to mimic in vacuum and in solution environment, respectively. Different configurations and dynamic properties are found in the two absolutely different environments, showing that the solvent condition plays an obvious role in the process of chain adsorption and diffusion on the hydrophobic surface. The chain all present as two-dimensional (2D) adsorption configuration on the surface. The adsorption energy of different chain lengths follows a linear function, and the average adsorption energy per segment is -1.58 kcal/mol. In addition, the diffusion coefficient (D) of such chains scales with the degree of polymerization (N) as N-3/2.

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