Molecular dynamics simulation of a Langmuir–Blodgett film

Moller, Michael A.; Tildesley, Dominic J.; Kim, K. S.; Quirke, N.

doi:10.1063/1.460071

Cited by 126 publications

(78 citation statements)

References 71 publications

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“…19,20 At high densities the assumption that the CH 3 and CH 2 groups can be modeled as united atoms tends to fail. Indeed simulations of alkane crystals 26,27 and dense monolayers of alkanes 28,29 show that united atom models do not describe the packing of alkane molecules correctly, and that it is important to take the hydrogen atoms explicitly into account. Because of the increased number of interaction sites, these ''all atoms models'' 16 are much more demanding with regard to their use in a simulation.…”

Section: Introductionmentioning

confidence: 99%

Computer simulations of vapor–liquid phase equilibria of n-alkanes

Smit

Karaborni

Siepmann

1995

The Journal of Chemical Physics

482

188

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For petrochemical applications knowledge of the critical properties of the n-alkanes is of interest even at temperatures where these molecules are thermally unstable. Computer simulations can determine the vapor-liquid coexistence curve of a large number of n-alkanes ranging from pentane ͑C 5 ͒ through octatetracontane ͑C 48 ͒. We have compared the predicted phase diagrams of various models with experimental data. Models which give nearly identical properties of liquid alkanes at standard conditions may have critical temperatures that differ by more than 100 K. A new n-alkane model has been developed by us that gives a good description of the phase behavior over a large temperature range. For modeling vapor-liquid coexistence a relatively simple united atom model was sufficient to obtain a very good agreement with experimental data; thus it appears not necessary to take the hydrogen atoms explicitly into account. The model developed in this work has been used to determine the critical properties of the long-chain alkanes for which experiments turned out to be difficult and contradictory. We found that for the long-chain alkanes ͑C 8 -C 48 ͒ the critical density decreases as a function of the carbon number. These simulations were made possible by the use of a recently developed simulation technique, which is a combination of the Gibbs-ensemble technique and the configurational-bias Monte Carlo method. Compared with the conventional Gibbs-ensemble technique, this method is several orders of magnitude more efficient for pentane and up to a hundred orders of magnitude for octatetracontane. This recent development makes it possible to perform routinely phase equilibrium calculations of complex molecules.

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Section: Introductionmentioning

confidence: 99%

Computer simulations of vapor–liquid phase equilibria of n-alkanes

Smit

Karaborni

Siepmann

1995

The Journal of Chemical Physics

482

188

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“…They suggested that titling maximises the van der Waals attraction between the chains by increasing the packing efficiency [227]. The tilting transition was attributed to the packing of the hydrogen atoms belonging to methylene groups on neighbouring molecules, meaning that the correct behaviour could only be accurately reproduced using all-atom (AA) and not united-atom (UA) force-fields [226]. Recent NEMD simulations by Ewen et al [10] showed that the use of AA force-fields is also critical to give accurate flow and particularly friction behaviour for OFM films under shear.…”

Section: Film Structurementioning

confidence: 99%

“…Moller et al [226] were the first to use EMD simulations to study the structure of OFM films (stearic acid) on solid (graphite) surfaces in 1991. They varied the size of the head group to study its effect on the tilt angle from the surface normal.…”

Section: Film Structurementioning

confidence: 99%

Advances in nonequilibrium molecular dynamics simulations of lubricants and additives

2018

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Nonequilibrium molecular dynamics (NEMD) simulations have provided unique insights into the nanoscale behaviour of lubricants under shear. This review discusses the early history of NEMD and its progression from a tool to corroborate theories of the liquid state, to an instrument that can directly evaluate important fluid properties, towards a potential design tool in tribology. The key methodological advances which have allowed this evolution are also highlighted. This is followed by a summary of bulk and confined NEMD simulations of liquid lubricants and lubricant additives, as they have progressed from simple atomic fluids to ever more complex, realistic molecules. The future outlook of NEMD in tribology, including the inclusion of chemical reactivity for additives, and coupling to continuum methods for large systems, is also briefly discussed.

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“…The long-range interactions were characterized with two different Lennard-Jones (LJ) potentials, one that was formulated for the study of liquid n-butane near its boiling point, termed LJ1 [37], and a LJ potential for generic hydrocarbon systems, referred to here as LJ2 [38]. The combined expression used to calculate the energy of the system in each case is thus…”

Section: Computational Detailsmentioning

confidence: 99%

Molecular dynamics simulations of the filling and decorating of carbon nanotubules

Mao¹,

Garg²,

1999

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Abstract. Carbon nanotubes (CNTs) have been proposed as excellent materials for the construction of new, precisely tailored ultrafiltration membranes and as promising fibres for the construction of new, stronger composite materials. In this paper classical molecular dynamics simulations are used to investigate the potential use of CNTs in these applications. Functional groups have been covalently attached to the walls of CNTs to provide more extensive interactions between these new fibres and a polymer matrix. We examine the effects of these attachments on the mechanical properties of the tubules. The diffusive molecular flow of methane, ethane and ethylene through single tubules at room temperature are also studied. The simulations predict normal-mode molecular diffusion for methane. However, diffusion that is intermediate between normal-mode and single-file diffusion is predicted for ethane and ethylene. These diffusion results are found to be similar to results predicted for molecular diffusion in zeolites.

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Molecular dynamics simulation of a Langmuir–Blodgett film

Cited by 126 publications

References 71 publications

Computer simulations of vapor–liquid phase equilibria of n-alkanes

Computer simulations of vapor–liquid phase equilibria of n-alkanes

Advances in nonequilibrium molecular dynamics simulations of lubricants and additives

Molecular dynamics simulations of the filling and decorating of carbon nanotubules

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