Mechanical and thermodynamic routes to the liquid-liquid interfacial tension and mixing free energy by molecular dynamics

Fuente: arXiv
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Main Authors: Ogawa, Rei, Kusudo, Hiroki, Omori, Takeshi, Smith, Edward R., Joly, Laurent, Merabia, Samy, Yamaguchi, Yasutaka
Format: Preprint
Published: 2024
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author Ogawa, Rei
Kusudo, Hiroki
Omori, Takeshi
Smith, Edward R.
Joly, Laurent
Merabia, Samy
Yamaguchi, Yasutaka
author_facet Ogawa, Rei
Kusudo, Hiroki
Omori, Takeshi
Smith, Edward R.
Joly, Laurent
Merabia, Samy
Yamaguchi, Yasutaka
contents In this study, we carried out equilibrium molecular dynamics (EMD) simulations of the liquid-liquid interface between two different Lennard-Jones components with varying miscibility, where we examined the relation between the interfacial tension and isolation free energy using both a mechanical and thermodynamic approach. Using the mechanical approach, we obtained a stress distribution around a quasi-one-dimensional (1D) EMD systems with a flat LL interface. From the stress distribution, we calculated the liquid-liquid interfacial tension based on Bakker's equation, which uses the stress anisotropy around the interface, and measures how it varies with miscibility. The second approach uses thermodynamic integration by enforcing quasi-static isolation of the two liquids to calculate the free energy. This uses the same EMD systems as the mechanical approach, with both extended dry-surface and phantom-wall (PW) schemes applied. When the two components were immiscible, the interfacial tension and isolation free energy were in good agreement, provided all kinetic and interaction contributions were included in the stress. When the components were miscible, the values were significantly different. From the result of PW for the case of completely mixed liquids, the difference was attributed to the additional free energy required to separate the binary mixture into single components against the osmotic pressure prior to the complete detachment of the two components, i.e., the free energy of mixing.
format Preprint
id arxiv_https___arxiv_org_abs_2409_10856
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Mechanical and thermodynamic routes to the liquid-liquid interfacial tension and mixing free energy by molecular dynamics
Ogawa, Rei
Kusudo, Hiroki
Omori, Takeshi
Smith, Edward R.
Joly, Laurent
Merabia, Samy
Yamaguchi, Yasutaka
Soft Condensed Matter
Chemical Physics
In this study, we carried out equilibrium molecular dynamics (EMD) simulations of the liquid-liquid interface between two different Lennard-Jones components with varying miscibility, where we examined the relation between the interfacial tension and isolation free energy using both a mechanical and thermodynamic approach. Using the mechanical approach, we obtained a stress distribution around a quasi-one-dimensional (1D) EMD systems with a flat LL interface. From the stress distribution, we calculated the liquid-liquid interfacial tension based on Bakker's equation, which uses the stress anisotropy around the interface, and measures how it varies with miscibility. The second approach uses thermodynamic integration by enforcing quasi-static isolation of the two liquids to calculate the free energy. This uses the same EMD systems as the mechanical approach, with both extended dry-surface and phantom-wall (PW) schemes applied. When the two components were immiscible, the interfacial tension and isolation free energy were in good agreement, provided all kinetic and interaction contributions were included in the stress. When the components were miscible, the values were significantly different. From the result of PW for the case of completely mixed liquids, the difference was attributed to the additional free energy required to separate the binary mixture into single components against the osmotic pressure prior to the complete detachment of the two components, i.e., the free energy of mixing.
title Mechanical and thermodynamic routes to the liquid-liquid interfacial tension and mixing free energy by molecular dynamics
topic Soft Condensed Matter
Chemical Physics
url https://arxiv.org/abs/2409.10856