Phase diagram of Lennard-Jones fluid confined in slit pores

Kaneko, Toshihiro; Mima, Toshiki; Yasuoka, Kenji

doi:10.1016/j.cplett.2010.03.048

Cited by 32 publications

(21 citation statements)

References 28 publications

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“…We also observe that A/N k B T is lower for smaller pores than larger pores, and thus smaller pores should likewise be expected to have a higher ODT value than the bulk. These results are fully consistent with previous studies by Gubbins and co-workers 27 and Kaneko and co-workers 47 .…”

Section: A Ideal Systemssupporting

confidence: 83%

“…Interestingly, A/N k B T of the central most confined region and the equivalent density bulk fluid appear to oscillate with respect to each other; the fluid state is lower in free energy for non-ideal separations whereas the confined solid is lower for ideal separations. This agrees with calculations by Kaneko and coworkers that suggest the freezing/melting points oscillate with separation 47 . This trend persists up to approximately six ideal layers, at which point the values of A/N k B T converge.…”

Section: The Role Of the Central Atomssupporting

confidence: 82%

“…Table I summarizes the ODT for ideal pore separations (i.e., integer multiples of the FCC layer spacing, 2 (1/6) (6/9)σ), for various wm values. We observe that as wm is increased, so too does T conf ODT , in agreement with previous work 27, 47 . The ODT is also shifted to higher temperatures as the pore separation is reduced.…”

Section: A Ideal Systemssupporting

confidence: 80%

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Confined fluid and the fluid-solid transition: Evidence from absolute free energy calculations

et al. 2012

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The debate on whether an organic fluid nanoconfined by mica sheets will undergo a fluid-tosolid transition as the fluid film thickness is reduced below a critical value has lasted over two decades. Extensive experimental and simulation investigations have thus far left this question only partially addressed. In this work we adapt and apply absolute free energy calculations to analyze the phase behavior of a simple model for nanoconfined fluids, consisting of spherical Lennard-Jones (LJ) molecules confined between LJ solid walls, which we use in combination with grand canonical molecular dynamics simulations. Absolute Helmholtz free energy calculations of the simulated nanoconfined systems directly support the existence of order-disorder phase transition as a function of decreasing wall separation, providing results in close agreement with previous experiments and detailed atomistic simulations.

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Section: A Ideal Systemssupporting

confidence: 83%

Section: The Role Of the Central Atomssupporting

confidence: 82%

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Confined fluid and the fluid-solid transition: Evidence from absolute free energy calculations

et al. 2012

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“…Thus the first order transition along the adsorption branch is due to (1) a liquid-solid transition in the contact layer and (2) a compressed gas to solid transition in the inner layer. It should be noted that the temperature 87K is above the bulk triple point 83.78K and the RDD shows that the 2D solid is square packed, as observed by other researchers [17,31,[41][42][43].…”

Section: Adsorption Of Argon In An Infinite Pore At 87kmentioning

confidence: 53%

On the adsorbate restructuring induced hysteresis of simple gas adsorption in slit micropores

Diao

Fan

et al. 2016

Chemical Engineering Journal

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Simulations of adsorption isotherms for simple gases in homogeneous slit pores with two open ends often show hysteresis, between condensation and evaporation branches. The hysteresis may result either, from the difference in the curvature of the interface separating the adsorbed and gas phases, or from molecular restructuring when the adsorbate is densely packed. The order-disorder transition that occurs in the second case, has also been observed experimentally for adsorption on a graphite surface, and is supported by molecular simulation [1,2]. In this paper we report a comprehensive set of GCMC simulations designed to explore the effects of pore size and temperature on the hysteresis loop induced by adsorbate restructuring. We report isotherms, isosteric heats, and microscopic analyses of the local density distribution, and the 2D and 3D radial density distributions. Local compressibilities reinforce the supposition that adsorbate restructuring is the origin of the ordering hysteresis.

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“…The simulations are carried out as follows: the system containing approximately 100.000 liquid molecules is first equilibrated for 60 ns at a constant temperature and pressure of T = 0.88 e/k B and P = 3.3 e/r 3 , respectively. Since confinement can move the liquidsolid transition line in the phase diagram [34], the vicinity to the melting point may affect our results, in the simulations and experiments alike. Temperature and pressure are kept constant using Toxvaerds implementation of the Nosé-Hoover thermostat and barostat [35].…”

Section: Background and Technical Aspectsmentioning

confidence: 90%

Can Confinement-Induced Variations in the Viscous Dissipation be Measured?

et al. 2012

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Liquids confined to molecular scales become anisotropic and often show pronounced self-organization such as layering. Although this effect is well accepted, it is still debated if confinement induces measurable changes of viscous friction. We use molecular dynamics to address this issue by simulating a Lennard-Jones liquid confined between a solid cylinder and an atomically smooth surface. The simulations reproduce the well-established variations of normal force, density, and diffusivity with the distance between wall and cylinder. We find high diffusivity and low density when the numbers of layers is in between integers. This observation seems to contradict most experimental results on the effective damping between atomic force microscope tips and substrates when interpreting them within continuum hydrodynamics used to connect liquid viscosity and diffusivity. This contradiction is resolved by directly extracting the damping that the tip experiences, which we achieve by using the fluctuationdissipation theorem; as in experiment, we find local minima in the damping near integer numbers of molecular layers and maxima in between. These variations correlate with distinct structural changes in the microscopic order of the fluid. We reconfirm that constitutive equations valid at macroscopic scales cannot be used to interpret confined liquids and finally conclude that viscous friction displays measurable, non-monotonic behavior with the degree of confinement.

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Phase diagram of Lennard-Jones fluid confined in slit pores

Cited by 32 publications

References 28 publications

Confined fluid and the fluid-solid transition: Evidence from absolute free energy calculations

Confined fluid and the fluid-solid transition: Evidence from absolute free energy calculations

On the adsorbate restructuring induced hysteresis of simple gas adsorption in slit micropores

Can Confinement-Induced Variations in the Viscous Dissipation be Measured?

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