Interfacial and coexistence properties of soft spheres with a short-range attractive Yukawa fluid: Molecular dynamics simulations

González‐Melchor, Minerva; Hernández-Cocoletzi, G.; López-Lemus, Jorge Armando; Ortega-Rodríguez, Alejandro; Orea, Pedro

doi:10.1063/1.3703507

Cited by 8 publications

(4 citation statements)

References 46 publications

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“…Apart from simple spherical models, during the last two decades the interfacial properties of molecular model systems have been investigated using both Monte Carlo and molecular dynamics techniques of a number of systems interacting through different intermolecular potentials, mostly LJ and Mie [2][3][4][5][6][7][8][9][10][11][12][13][14][15] , but also systems that interact via the hard-core Yukawa potential [16][17][18][19][20] , and the square-well (SW) potential 5,9,17,[21][22][23][24][25][26][27][28] . In fact, whereas the computation of interfacial properties of polymer models have been the subject of a number of recent papers, [29][30][31][32][33] results for the well known fully-flexible SW model, in which square-well segments (monomers) of diameter σ and potential range λ are tangentially bonded to form molecular chains are scarce.…”

Section: Introductionmentioning

confidence: 99%

Vapour–liquid interfacial properties of square-well chains from density functional theory and Monte Carlo simulation

Martínez-Ruiz

Blas

Bravo

et al. 2017

Phys. Chem. Chem. Phys.

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The statistical associating fluid theory for attractive potentials of variable range (SAFT-VR) density functional theory (DFT) developed by [Gloor et al., J. Chem. Phys., 2004, 121, 12740-12759] is used to predict the interfacial behaviour of molecules modelled as fully-flexible square-well chains formed from tangentially-bonded monomers of diameter σ and potential range λ = 1.5σ. Four different model systems, comprising 4, 8, 12, and 16 monomers per molecule, are considered. In addition to that, we also compute a number of interfacial properties of molecular chains from direct simulation of the vapour-liquid interface. The simulations are performed in the canonical ensemble, and the vapour-liquid interfacial tension is evaluated using the wandering interface (WIM) method, a technique based on the thermodynamic definition of surface tension. Apart from surface tension, we also obtain density profiles, coexistence densities, vapour pressures, and critical temperature and density, paying particular attention to the effect of the chain length on these properties. According to our results, the main effect of increasing the chain length (at fixed temperature) is to sharpen the vapour-liquid interface and to increase the width of the biphasic coexistence region. As a result, the interfacial thickness decreases and the surface tension increases as the molecular chains get longer. The interfacial thickness and surface tension appear to exhibit an asymptotic limiting behaviour for long chains. A similar behaviour is also observed for the coexistence densities and critical properties. Agreement between theory and simulation results indicates that SAFT-VR DFT is only able to predict qualitatively the interfacial properties of the model. Our results are also compared with simulation data taken from the literature, including the vapour-liquid coexistence densities, vapour pressures, and surface tension.

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Section: Introductionmentioning

confidence: 99%

Vapour–liquid interfacial properties of square-well chains from density functional theory and Monte Carlo simulation

Martínez-Ruiz

Blas

Bravo

et al. 2017

Phys. Chem. Chem. Phys.

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“…This contrasts with the modeling of the core hardness as a power-law, (1/x) n . In this case, even considering extremely large exponents, n > 200, the differences in the coexistence properties between the approximation and the hard-core case do not vanish 32 . A final remarkable issue is that the data series for α = 400 is indistinguishable from the one for α = 800.…”

Section: Resultsmentioning

confidence: 89%

“…It is worth mentioning that the constant-force approximation contrasts previous works where the core hardness is modeled by adding a high-exponent power-law contribution 32,39,40 .…”

Section: Introductionmentioning

confidence: 98%

“…Thus, for a given system, when surface tension and coexistence data of independent sources match each other, one can expect a match for other thermodynamic properties. Furthermore, obtaining the surface tension turns out to be more computationally demanding as the potential range is shortened [30][31][32] . This is specially true when dealing with hard-cores.…”

Section: Introductionmentioning

confidence: 99%

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Constant-force approach to discontinuous potentials

Orea

Odriozola

2013

The Journal of Chemical Physics

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Aiming to approach the thermodynamical properties of hard-core systems by standard molecular dynamics simulation, we propose setting a repulsive constant-force for overlapping particles. That is, the discontinuity of the pair potential is replaced by a linear function with a large negative slope. Hence, the core-core repulsion, usually modeled with a power function of distance, yields a large force as soon as the cores slightly overlap. This leads to a quasi-hardcore behavior. The idea is tested for a triangle potential of short range. The results obtained by replica exchange molecular dynamics for several repulsive forces are contrasted with the ones obtained for the discontinuous potential and by means of replica exchange Monte Carlo. We found remarkable agreements for the vapor-liquid coexistence densities as well as for the surface tension.

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Phase behavior of colloids and proteins in aqueous suspensions: Theory and computer simulations

Valadez-Pérez

Benavides²,

Schöll-Paschinger³

et al. 2012

The Journal of Chemical Physics

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The fluid phase behavior of colloidal suspensions with short-range attractive interactions is studied by means of Monte Carlo computer simulations and two theoretical approximations, namely, the discrete perturbation theory and the so-called self-consistent Ornstein-Zernike approximation. The suspensions are modeled as hard-core attractive Yukawa (HCAY) and Asakura-Oosawa (AO) fluids. A detailed comparison of the liquid-vapor phase diagrams obtained through different routes is presented. We confirm Noro-Frenkel's extended law of scaling according to which the properties of a short-ranged fluid at a given temperature and density are independent of the detailed form of the interaction, but just depend on the value of the second virial coefficient. By mapping the HCAY and AO fluids onto an equivalent square-well fluid of appropriate range at the critical point we show that the critical temperature as a function of the effective range is independent of the interaction potential, i.e., all curves fall in a master curve. Our findings are corroborated with recent experimental data for lysozyme proteins.

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Interfacial and coexistence properties of soft spheres with a short-range attractive Yukawa fluid: Molecular dynamics simulations

Cited by 8 publications

References 46 publications

Vapour–liquid interfacial properties of square-well chains from density functional theory and Monte Carlo simulation

Vapour–liquid interfacial properties of square-well chains from density functional theory and Monte Carlo simulation

Constant-force approach to discontinuous potentials

Phase behavior of colloids and proteins in aqueous suspensions: Theory and computer simulations

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