Fick diffusion coefficients via molecular dynamics: An alternative approach in the Fourier domain
Mutual diffusion coefficient data are required for several systems of scientific and engineering interest to properly describe mass transport phenomena over a wide range of pressures, temperatures, and compositions. In this work, we calculated Fick diffusion coefficients for some CO2 and n-alkane mi...
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Veröffentlicht in: | Journal of molecular liquids 2021-05, Vol.329, p.115460, Article 115460 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Mutual diffusion coefficient data are required for several systems of scientific and engineering interest to properly describe mass transport phenomena over a wide range of pressures, temperatures, and compositions. In this work, we calculated Fick diffusion coefficients for some CO2 and n-alkane mixtures at high pressures using a new method, which we derived by introducing modifications to the Fourier Correlation Method (FCM) originally proposed by Nichols and Wheeler [I&EC Research, 54, 12,156–12,164 (2015)]. The modified FCM (mFCM) results were validated through comparisons with experimental data and with Fick coefficients calculated by employing well-established Molecular Dynamics methodologies. The new approach has some interesting advantages, such as providing Fick coefficients for molecular systems directly through a single equilibrium calculation, in contrast to traditional methods in which an extra calculation is needed to obtain the so-called thermodynamic factor. It is shown that the new approach considerably reduces the finite-size effect of the simulation box on the calculated diffusion coefficients, which are thus obtained in the thermodynamic limit.
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•A new methodology to calculate binary Fick diffusion coefficients via EMD simulations.•An innovative approach to calculate the thermodynamic factor in the Fourier domain with the Ornstein-Zernike theory.•Calculation of Fick diffusivities of different CO2 and n-alkane mixtures at reservoir conditions.•Evaluation of finite-size effects on mutual diffusivities. |
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ISSN: | 0167-7322 1873-3166 |
DOI: | 10.1016/j.molliq.2021.115460 |