Communication: Truncated non-bonded potentials can yield unphysical behavior in molecular dynamics simulations of interfaces

Fitzner, Martin; Joly, Laurent; Ma, Ming; Sosso, Gabriele C.; Zen, Andrea; Michaelides, Angelos

doi:10.1063/1.4997698

Cited by 15 publications

(6 citation statements)

References 51 publications

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“…A direct-space cutoff of 15 Å was used for both the LJ and the Coulombic interactions and the long-range part of the Coulombic interactions was calculated using the PPPM method with a tolerance of 1 × 10 –4 in the energy. We note here that previous studies ,, have shown that the simulated contact angles obtained from MD simulations can be sensitive to the cutoff length used to truncate the LJ interactions. For this reason, we have utilized a large LJ cutoff length of 15 Å to carry out the work of adhesion simulations reported in this study.…”

Section: Theoretical Methodsmentioning

confidence: 74%

Insights on the Role of Many-Body Polarization Effects in the Wetting of Graphitic Surfaces by Water

2017

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It is well-known that atoms in a substrate placed in contact with a polar solvent like water experience a finite electric field from the solvent molecules. Nevertheless, the effect of this electric field on the wetting properties of the substrate remains unknown. In this study, by carrying out molecular dynamics (MD) simulations with force field parameters derived from ab initio simulations, we develop a theoretical framework to quantify the role of the polarization of graphene in the wetting of graphitic surfaces by water. Our study shows that a self-consistent modeling of the polarization of graphene yields a water contact angle on graphite that is remarkably different from the contact angle that results if the polarization energy is instead modeled implicitly using a Lennard-Jones potential, a typical approximation used in all previous MD simulation studies on the wetting of graphitic surfaces. Our findings reveal that polarization has a more pronounced effect on the interfacial entropy of water compared to dispersion interaction. Consequently, polarization and dispersion interactions contribute differently to the wetting of graphitic surfaces. Our study significantly advances our understanding of the water–graphene interface, which is important for practical applications of graphene-based nanomaterials in osmotic power harvesting and seawater desalination.

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Section: Theoretical Methodsmentioning

confidence: 74%

Insights on the Role of Many-Body Polarization Effects in the Wetting of Graphitic Surfaces by Water

2017

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“…Additionally, we have performed independent test simulations to make sure that the topological wetting is free of the artifacts due to short cutoff distance, as previously reported. 55 In these test simulations, we increased the cutoff distance value to 25.6 Å, where the two independent sets of simulations with the mW model and with the SPC/E water model, respectively, show a water nanodroplet with ACA > 0°on a square-loop surface but in the complete-wetting state on the corresponding planar surface (Movies S12 vs S13 and S14 vs S15). Topological Wetting States.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Turning a Superhydrophilic Surface Weakly Hydrophilic: Topological Wetting States

et al. 2020

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For water droplets placed on a rough or structured surface, two distinct wetting states commonly observed are either the Wenzel state (droplets wet the surface without showing air pockets beneath the droplets) or the Cassie state (droplets reside on top of the structure with air pockets trapped beneath the droplets). Herein, we show molecular dynamics (MD) simulation evidence of a previously unreported wetting behavior, i.e., the rise of multiple Wenzel states on the structured surfaces whose flat-surface counterparts are superhydrophilic (i.e., complete wetting surfaces with the hallmark of zero contact angle for water droplets). Specifically, our MD simulations show that on the structured surfaces with topology of closed-loop nanowalls/nanochannels, the water droplet can exhibit multiple Wenzel wetting states with the apparent contact angles >0°. We name these distinct multiple Wenzel states as “topological wetting states” because their existence can be attributed to the topology of the closed-loop nanowalls/nanochannels. Regardless of the shape of the closed loops, such topological wetting states can always arise due to the topological invariant (i.e., all closed loops entail the same topological genus value). This unusual wetting behavior is contrary to the conventional view (and to the prediction of the Wenzel equation), namely, a rough hydrophilic surface should have stronger hydrophilicity than its flat-surface counterpart.

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“…For bulk homogeneous systems, this is typically a sufficient approximation. However, for inhomogeneous systems such as vapor–liquid interfaces, − lipid bilayers, and water droplets on solid surfaces, ignoring long-range interactions introduces artifacts. For example, Caleman et al found that surface tensions of 146 organic liquids using the GAFF and OPLS-AA force fields with an 11 Å cutoff were consistently too low compared to the experiment, with an average deviation of approximately 20% .…”

Section: Introductionmentioning

confidence: 99%

Vapor–Liquid Equilibrium Simulations of Hydrocarbons Using Molecular Dynamics with Long-Range Lennard-Jones Interactions

Harrison

2019

Energy Fuels

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Because of exposure of injected fuel to extreme temperatures and pressures in modern diesel and jet engines, there is much interest in understanding vapor−liquid equilibrium (VLE), interfacial behavior, and critical properties of hydrocarbon mixtures. Molecular dynamics (MD) simulations with long-range dispersion interactions can be used to study liquid−vapor interfacial properties. In this work, the accuracy of three force fields (CHARMM, OPLS-AA, and TraPPE-UA) is assessed by using MD simulations with the Lennard-Jones particle-mesh Ewald method to examine the VLE behavior of 12 pure hydrocarbons. While the TraPPE-UA potential yields significantly better critical temperature predictions, all three force fields predict critical densities and pressures with about the same accuracy. Surface tensions calculated using the TraPPE-UA force field are too high compared to experiment; values using the CHARMM and OPLS-AA potentials tend to be more accurate at lower temperatures and then decrease too quickly as temperature increases. Simulations of binary mixtures show that both the CHARMM and TraPPE-UA potentials predict the same liquid-and vapor-phase compositions as a function of overall mole fraction. Not surprisingly, the composition of the interfacial region is correlated with the surface tension values of the pure components. Pressure versus mole fraction phase diagrams were quantitatively reproduced by TraPPE-UA and only qualitatively reproduced by the CHARMM force field. Given the lack of phase equilibrium data used in the parameterization of the CHARMM potential, its ability to reproduce many aspects of VLE behavior is impressive. This work demonstrates the power of MD simulations for examining the phase behavior of hydrocarbons under conditions that are difficult to achieve experimentally.

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Communication: Truncated non-bonded potentials can yield unphysical behavior in molecular dynamics simulations of interfaces

Cited by 15 publications

References 51 publications

Insights on the Role of Many-Body Polarization Effects in the Wetting of Graphitic Surfaces by Water

Insights on the Role of Many-Body Polarization Effects in the Wetting of Graphitic Surfaces by Water

Turning a Superhydrophilic Surface Weakly Hydrophilic: Topological Wetting States

Vapor–Liquid Equilibrium Simulations of Hydrocarbons Using Molecular Dynamics with Long-Range Lennard-Jones Interactions

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