Droplet spreading driven by van der Waals force: a molecular dynamics study

Wu, Congmin; Qian, Tiezheng; Sheng, Ping

doi:10.1088/0953-8984/22/32/325101

Cited by 13 publications

(10 citation statements)

References 42 publications

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“…An interesting approach for resolving the issue of volatility in MD simulations has been proposed recently in Ref. [162], where the authors use a quarter of a cylindrical liquid drop confined by a rectangular wedge formed by two atomistic semi-infinite fcc walls (minus their overlap). This quarter of a cylindrical liquid drop is covered by an immiscible fluid of equal density and viscosity, and the confinement is completed by two additional homogeneous walls enclosing the covering fluid; periodic boundary conditions apply in the longitudinal direction.…”

Section: Molecular Dynamics Simulations For Simple or Polymeric Liquidsmentioning

confidence: 99%

Precursor films in wetting phenomena

Popescu

Oshanin

Dietrich

et al. 2012

J. Phys.: Condens. Matter

190

227

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The spontaneous spreading of non-volatile liquid droplets on solid substrates poses a classic problem in the context of wetting phenomena. It is well known that the spreading of a macroscopic droplet is in many cases accompanied by a thin film of macroscopic lateral extent, the so-called precursor film, which emanates from the three-phase contact line region and spreads ahead of the latter with a much higher speed. Such films have been usually associated with liquid-on-solid systems, but in the last decade similar films have been reported to occur in solid-on-solid systems. While the situations in which the thickness of such films is of mesoscopic size are fairly well understood, an intriguing and yet to be fully understood aspect is the spreading of microscopic, i.e. molecularly thin, films. Here we review the available experimental observations of such films in various liquid-on-solid and solid-on-solid systems, as well as the corresponding theoretical models and studies aimed at understanding their formation and spreading dynamics. Recent developments and perspectives for future research are discussed.

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Section: Molecular Dynamics Simulations For Simple or Polymeric Liquidsmentioning

confidence: 99%

Precursor films in wetting phenomena

Popescu

Oshanin

Dietrich

et al. 2012

J. Phys.: Condens. Matter

190

227

View full text Add to dashboard Cite

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“…12,13 Previous MD simulations of the solid-liquid interface to determine the molecular-kinetic theory for water droplets on a solid surface indicate that diffusion of the water droplet and its governing mechanism are complex. [12][13][14][15] However, in these simulations, the interactions between the water droplet and the solid surface were modeled using the Lennard-Jones 12-6 pair potential which is ideal for describing van der Waals interactions but is unable to capture electrostatic contributions to interatomic interactions at the solid-liquid interface. 16,17 Electrochemical or electrostatic interactions at the solid-liquid interface may be modeled using a variable charge bond order reactive potential such as ReaxFF or COMB3.…”

Section: Introductionmentioning

confidence: 99%

Optimized utilization of COMB3 reactive potentials in LAMMPS

Slapikas

Dabo

Sinnott

2020

The Journal of Chemical Physics

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An investigation to optimize the application of the third-generation charge optimized many-body (COMB3) interatomic potential and associated input parameters was carried out through the study of solid-liquid interactions in classical molecular dynamics (MD) simulations. The rates of these molecular interactions are understood though the wetting rates of water nano droplets on a bare copper (111) surface. Implementing the Langevin thermostat, the influence of simulation time step, the number of atoms in the system, the frequency at which charge equilibration is performed, and the temperature relaxation rate are all examined. The results indicate that time steps of 0.4 fs are possible when using longer relaxation times for the system temperature, which is almost double the typical time step used for reactive potentials. The use of the QEq charge equilibration allows for a fewer atomic layers to be used in the Cu slab. In addition, charge equilibrium schemes do not need to be performed every time step to ensure accurate charge transfer. Interestingly, the rate of wetting for the nanodroplets is dominantly dependent on the temperature relaxation time which are predicted to significantly change the viscosity of the water droplets. This work provides a pathway for optimizing simulations using the COMB3 reactive interatomic potential.

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“…20 These MD simulations have typically used rigid fixed charge water potentials such as extended single-point charge (SPC/ E) 21 and TIP4P 22 which do an excellent job of describing molecular adsorption to the underlying surface but allow for only limited (if any) variations in atomic charges in response to changes in the surrounding environment. Additionally, the standard Lennard−Jones (LJ) pairwise potential used to describe liquid/solid interactions 23,24 lacks the complexity needed to capture both the underlying physics of the liquid water and the chemical bonding in solid metals and metal oxides.…”

Section: Introductionmentioning

confidence: 99%

Effect of Surface Chemistry on Water Interaction with Cu(111)

et al. 2016

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The interfacial dynamics of water in contact with bare, oxidized, and hydroxylated copper surfaces are examined using classical molecular dynamics (MD) simulations. A third-generation charge-optimized many-body (COMB3) potential is used in the MD simulations to investigate the adsorption of water molecules on Cu(111), and the results are compared to the findings of density functional theory (DFT) calculations. The adsorption energies and structures predicted by COMB3 are generally consistent with those determined with DFT. The COMB3 potential is then used to investigate the wetting behavior of water nanodroplets on Cu(111) at 20, 130, and 300 K. At room temperature, the simulations predict that the spreading rate of the base radius, R0, of a water droplet with a diameter of about 1.5 nm exhibits a spreading rate of R0 ≈ t(0.16) and a final base radius of 3.5 nm. At 20 and 130 K, water droplets are predicted to retain their structure after adsorption on Cu(111) and to undergo minimal spreading in agreement with scanning tunneling microscopy data. When the same water droplet encounters a reconstructed, oxidized Cu(111) surface, the classical MD simulations predict wetting with a spreading rate of R ≈ t(0.14) and a final base radius of 3.0 nm. Similarly, our MD simulations predict a spreading rate of R ≈ t(0.14) and a final base radius of 2.5 nm when water encounters OH-covered Cu(111). These results indicate that oxidation and hydroxylation cause a reduction in the degree of spreading and final base radius that is directly associated with a decreased spreading rate for water nanodroplets on copper.

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Droplet spreading driven by van der Waals force: a molecular dynamics study

Cited by 13 publications

References 42 publications

Precursor films in wetting phenomena

Precursor films in wetting phenomena

Optimized utilization of COMB3 reactive potentials in LAMMPS

Effect of Surface Chemistry on Water Interaction with Cu(111)

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