Molecular dynamics simulation of the orthobaric densities and surface tension of water

Alejandre, José; Tildesley, Dominic J.; Chapela, Gustavo A.

doi:10.1063/1.469505

Cited by 659 publications

(641 citation statements)

References 38 publications

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“…These corrections can be easily incorporated in simulations involving homogeneous phases without the presence of the interface, as is the case of simulations implemented using the Gibbs ensemble or the Gibbs-Duhem integration techniques. In contrast, it is not straightforward to estimate the tail correction in simulations of inhomogeneous systems, 24,42 so the results reported in Tables I and II correspond to truncated interactions with no long-range corrections. The large value of the cutoff distance used in this work ensures that the contribution to the coexistence properties due to the tail correction is small.…”

Section: Resultsmentioning

confidence: 90%

“…It is customary to report the thickness of the interface in terms of the "10-90" thickness ͑t͒, which is related to d by t = 2.197 2d. Considering the hyperbolic tangent approximation for the density profile, it can be shown that an estimate of the tail correction to the surface tension due to the truncation of the LJ interaction is given by 24,60 …”

Section: Methodsmentioning

confidence: 99%

“…The determination of the surface tension of water by computer simulation has been the subject of several studies. [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] In the majority of these studies, a slab of liquid is placed in contact with vapor and the surface tension is computed from a mechanical route which requires the calculation of the pressure tensor. 39 A survey of the literature reveals that values of the surface tension from different authors differ in some cases considerably.…”

Section: Introductionmentioning

confidence: 99%

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Surface tension of the most popular models of water by using the test-area simulation method

Vega

Miguel²

2007

The Journal of Chemical Physics

709

105

699

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We consider the calculation of the surface tension from simulations of several models of water, such as the traditional TIP3P, SPC, SPC/E, and TIP4P models, and the new generation of TIP4P-like models including the TIP4P/Ew, TIP4P/Ice, and TIP4P/2005. We employ a thermodynamic route proposed by Gloor et al. ͓J. Chem. Phys. 123, 134703 ͑2005͔͒ to determine the surface tension that involves the estimate of the change in free energy associated with a small change in the interfacial area at constant volume. The values of the surface tension computed from this test-area method are found to be fully consistent with those obtained from the standard mechanical route, which is based on the evaluation of the components of the pressure tensor. We find that most models do not reproduce quantitatively the experimental values of the surface tension of water. The best description of the surface tension is given by those models that provide a better description of the vapor-liquid coexistence curve. The values of the surface tension for the SPC/E and TIP4P/Ew models are found to be in reasonably good agreement with the experimental values. From the present investigation, we conclude that the TIP4P/2005 model is able to accurately describe the surface tension of water over the whole range of temperatures from the triple point to the critical temperature. We also conclude that the test area is an appropriate methodological choice for the calculation of the surface tension not only for simple fluids, but also for complex molecular polar fluids, as is the case of water.

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Section: Resultsmentioning

confidence: 90%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Surface tension of the most popular models of water by using the test-area simulation method

Vega

Miguel²

2007

The Journal of Chemical Physics

709

105

699

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“…51,[82][83][84][85] where F i is the density, z 0 is the position of the Gibbs dividing surface, and d is the adjustable parameter related to the interfacial thickness. A common practice for defining the interfacial thickness for the liquid-vapor interface is the "10-90" criterion, 51,82,84,85 which defines the interfacial thickness to be the distance between two positions where the density varies from 10 to 90% of the density of the bulk phase. However, defining the thickness for a complicated interface such as the oil-water interface in the presence of a surfactant is not a trivial matter.…”

Section: Equilibrated System: Surfactant Conformation and Interface Fmentioning

confidence: 99%

Molecular Dynamics Study of a Surfactant-Mediated Decane−Water Interface: Effect of Molecular Architecture of Alkyl Benzene Sulfonate

Jang¹,

Lin²,

Maiti³

et al. 2004

J. Phys. Chem. B

274

206

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The effect of molecular architecture of a surfactant, particularly the attachment position of benzene sulfonate on the hexadecane backbone, at the decane-water interface was investigated using atomistic MD simulations. We consider a series of surfactant isomers in the family of alkyl benzene sulfonates, denoted by m-C16, indicating a benzene sulfonate group attached to the mth carbon in a hexadecane backbone. The equilibrated model systems showed a well-defined interface between the decane and water phases. We find that surfactant 4-C16 has a more compact packing, in terms of the interfacial area and molecular alignment at the interface, than other surfactants simulated in this study. Furthermore, surfactant 4-C16 leads to the most stable interface by having the lowest interface formation energy. The interfacial thickness is the largest in the case of surfactant 4-C16, with the thickness decreasing when the benzene sulfonate is located farther from the attachment position of 4-C16 (the 4th carbon). The interfacial tension profile was calculated along the direction perpendicular to the interface using the Kirkwood-Buff theory. From the comparison of the interfacial tension obtained from the interfacial tension profile, we found that surfactant 4-C16 induces the lowest interfacial tension and that the interfacial tension increases with decreasing interfacial thickness as a function of the attachment position of benzene sulfonate. Such a relationship between the interfacial thickness and interfacial tension is rationalized in terms of the miscibility of the alkyl tail of surfactant m-C16 with decane by comparing the "effective" length of the alkyl tail with the average end-to-end length of decane. Among the surfactants, the effective length of the 4-C16 alkyl tail (9.53 ( 1.36 Å) was found to be closest to that of decane (9.97 ( 1.03 Å), which is consistent with the results from the density profile and the interfacial tension profile.

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“…Yet, this value of the dipole moment is still well below the threshold value of m ‫ء‬ 5 [8], above which gas-liquid phase coexistence is suppressed. In fact, the value m ‫ء‬ 4 is comparable to that for the SPC͞E model of water (m ‫ء‬ 3.5) [13]. All simulations were performed at a reduced temperature T ‫ء‬ k B T ͞e 3.5 (k B is the Boltzmann's constant), which is approximately 30% below the critical temperature T ‫ء‬ c 5.07 [8].…”

mentioning

confidence: 99%

Coil-Globule Transition in Gas-Liquid Nucleation of Polar Fluids

1998

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We report computer simulations of homogeneous gas-liquid nucleation in a model for strongly polar fluids. We find that, in the early stages of the nucleation process, chainlike clusters are formed. Beyond a certain size, these collapse to form compact spherical clusters. However, the interface of the collapsed nuclei differs markedly from the planar interface. Classical nucleation theory underestimates both the size of the critical nucleus and the height of the nucleation barrier. [S0031-9007(98) PACS numbers: 64.60. Qb, 75.50.Mm, 82.60.Nh, 82.65.Dp The spontaneous condensation of water droplets in the vapor phase is probably the best known example of homogeneous nucleation of a polar fluid. However, best known is not the same as best understood. In fact, recent experiments indicate that classical nucleation theory [1] seriously overestimates the rate of nucleation for strongly polar substances, such as acetonitrile [2], although, surprisingly, it works well for water [3].The most important factor determining the gas-liquid nucleation rate is the height of the free-energy barrier for the formation of a critical nucleus. Classical nucleation theory (CNT) assumes that the nuclei at the top of the nucleation barrier are compact spherical objects that behave like small droplets of bulk liquid. Recent computer simulations on a nonpolar (Lennard-Jones) fluid support this picture [4]. However, for polar fluids, the nature of the critical nucleus is still under debate. Wright et al. [2] suggest that, for polar liquids, the critical nucleus is a prolate spheroid-thus increasing the surface-to-volume ratio, and thereby the nucleation barrier. The orientational distribution of dipoles inside this cluster is assumed to have cylindrical symmetry. Abraham [5] proposed a model in which the dipoles are assumed to be oriented perpendicular to the interface. This would give rise to a size-dependent surface tension due to the effect of surface curvature on the dipole-dipole interaction. However, both pictures are at odds with the findings of a recent density-functional study of the critical nucleus of a dipolar model fluid (the Stockmayer fluid) [6]. This study indicated that the dipoles on the liquid side of the interface of critical nuclei are oriented parallel to the surface, rather than perpendicular. Unfortunately, the applicability of the density-functional theory is limited to relatively weak polar fluids.In the present Letter, we present direct numerical simulations of the structure and free energy of precritical and postcritical nuclei of a strongly polar Stockmayer fluid. The Stockmayer potential is given byHere e is the Lennard-Jones well depth, s is the LennardJones diameter, m i denotes the dipole moment of particle i, and r ij is the vector joining particles i and j. The equilibrium phase behavior of this system has been studied in detail by computer simulation [7,8] and by theory [9,10]. The simulations suggest that attractive dispersion forces are essential for the existence of liquidvapor phase coexistence [7...

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Molecular dynamics simulation of the orthobaric densities and surface tension of water

Cited by 659 publications

References 38 publications

Surface tension of the most popular models of water by using the test-area simulation method

Surface tension of the most popular models of water by using the test-area simulation method

Molecular Dynamics Study of a Surfactant-Mediated Decane−Water Interface: Effect of Molecular Architecture of Alkyl Benzene Sulfonate

Coil-Globule Transition in Gas-Liquid Nucleation of Polar Fluids

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