Simulation of self-diffusion of point-like and finite-size tracers in stochastically reconstructed Vycor porous glasses

1999 ◽  
Vol 111 (6) ◽  
pp. 2735-2743 ◽  
Author(s):  
M. E. Kainourgiakis ◽  
E. S. Kikkinides ◽  
A. K. Stubos ◽  
N. K. Kanellopoulos
Keyword(s):  
Finite Size ◽  
Porous Glasses ◽  
Self Diffusion

scholarly journals Self-Diffusion Coefficients of Methane/n-Hexane Mixtures at High Pressures: An Evaluation of the Finite-Size Effect and a Comparison of Force Fields

2019 ◽  
Author(s):  
Thiago José Pinheiro dos Santos ◽  
Charlles Abreu ◽  
Bruno Horta ◽  
Frederico W. Tavares
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficients ◽  
High Pressures ◽  
Force Fields ◽  
Transport Coefficients ◽  
Finite Size ◽  
Finite Size Effect ◽  
Self Diffusion ◽  
Analytical Correction ◽  
Dynamics Simulations

Mass transport coefficients play an important role in process design and in compositional grading of oil reservoirs. As experimental measurements of these properties can be costly and hazardous, Molecular Dynamics simulations emerge as an alternative approach. In this work, we used Molecular Dynamics to calculate the self-diffusion coefficients of methane/n-hexane mixtures at different conditions, in both liquid and supercritical phases. We evaluated how the finite box size and the choice of the force field affect the calculated properties at high pressures. Results show a strong dependency between self-diffusion and the simulation box size. The Yeh-Hummer analytical correction [J. Phys. Chem. B, 108, 15873 (2004)] can attenuate this effect, but sometimes makes the results depart from experimental data due to issues concerning the force fields. We have also found that different all-atom and united-atom models can produce biased results due to caging effects and to different dihedral configurations of the n-alkane.

scholarly journals Self-Diffusion Coefficients of Methane/n-Hexane Mixtures at High Pressures: An Evaluation of the Finite-Size Effect and a Comparison of Force Fields

2019 ◽  
Author(s):  
Thiago José Pinheiro dos Santos ◽  
Charlles Abreu ◽  
Bruno Horta ◽  
Frederico W. Tavares
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficients ◽  
High Pressures ◽  
Force Fields ◽  
Transport Coefficients ◽  
Finite Size ◽  
Finite Size Effect ◽  
Self Diffusion ◽  
Analytical Correction ◽  
Dynamics Simulations

Mass transport coefficients play an important role in process design and in compositional grading of oil reservoirs. As experimental measurements of these properties can be costly and hazardous, Molecular Dynamics simulations emerge as an alternative approach. In this work, we used Molecular Dynamics to calculate the self-diffusion coefficients of methane/n-hexane mixtures at different conditions, in both liquid and supercritical phases. We evaluated how the finite box size and the choice of the force field affect the calculated properties at high pressures. Results show a strong dependency between self-diffusion and the simulation box size. The Yeh-Hummer analytical correction [J. Phys. Chem. B, 108, 15873 (2004)] can attenuate this effect, but sometimes makes the results depart from experimental data due to issues concerning the force fields. We have also found that different all-atom and united-atom models can produce biased results due to caging effects and to different dihedral configurations of the n-alkane.

Concentration-Dependent Self-Diffusion of Water in Aqueous Solutions of Lithium Chloride Confined to Porous Glasses

2013 ◽  
Vol 44 (7) ◽  
pp. 827-836 ◽  
Author(s):  
S. Beckert ◽  
M. Gratz ◽  
J. Kullmann ◽  
D. Enke ◽  
F. Stallmach
Keyword(s):  
Aqueous Solutions ◽  
Lithium Chloride ◽  
Porous Glasses ◽  
Self Diffusion

NMR Study of Adsorbate Self-Diffusion in Porous Glasses

1983 ◽  
Vol 66 (1) ◽  
pp. 69-72 ◽  
Author(s):  
JORG KARGER ◽  
JORG LENZNER ◽  
HARRY PFEIFER ◽  
HARTMUT SCHWABE ◽  
WOLFGANG HEYER ◽  
...  
Keyword(s):  
Porous Glasses ◽  
Self Diffusion ◽  
Nmr Study

Self-Diffusion in Molten Lithium. Isotopic mass dependence

1971 ◽  
Vol 26 (1) ◽  
pp. 85-93 ◽  
Author(s):  
J. S. Murday ◽  
R. M. Cotts
Keyword(s):  
Melting Point ◽  
Diffusion Coefficients ◽  
Isotopic Ratio ◽  
Spin Echo ◽  
Finite Size ◽  
Liquid Sodium ◽  
Published Data ◽  
Self Diffusion ◽  
Gradient Technique ◽  
Resonance Spin

Abstract The liquid state self-diffusion coefficients of Li6 and Li7 in isotopically enriched Li6 and Li7 metal and in several isotopic alloys have been measured by the nuclear magnetic resonance spin echo, pulsed magnetic gradient technique. At the melting point 180.5 °C, the self diffusion co­efficients are measured as Dm6= (6.8 + 0.7) · 10-5 cm2/sec for Li6 in 99% Li6, and Dm7 = (5.8 ± 0.6) -10-5 cm2/sec for Li7 in 99.9% Li7. The ratio of measured values (Dm6/Dm7) = 1.18 ± 0.07, which is greater than the square root of the mass ratio, (m7/m6) 1/2 = 1.08. The isotopic ratio of self diffusion coefficients is observed to be less than the ratio of the mutual diffusion coefficients in almost pure Li6 and almost pure Li7, (Dᴍm6/Dᴍm7) = 1.35, and the viscosity ratio, (η7/η6) = 1.44. The dependence of D upon isotopic alloy concentration appears to be relatively weak and linear in all but the very low concentrations. As a test of the experimental method, D was measured in liquid Na, H2O , and D2O . In liquid sodium at the melting point, D = (3.7 + 0.3) • 10-5 cm2/sec. The Na measurement and the values of D in water are about 5% below other published data, but they are in agreement within experimental uncertainties. Results of this experiment contain syste­matic corrections amounting to 15 - 20% caused principally by the finite size of the droplets of the liquid metal samples. The corrections as well as the limitations of the technique in measurement of self diffusion coefficients in metals are discussed

Sign in / Sign up

Export Citation Format

Share Document