Structure of Physisorbed Overlayers of Dipolar Molecules: A Combined Study by Atomic-Beam Scattering and Molecular Dynamics

Ruiz‐Suárez, J. C.; Klein, Michael L.; Moller, Michael A.; Rowntree, P.; Scoles, G.; Xu, Jia

doi:10.1103/physrevlett.61.710

Cited by 55 publications

(8 citation statements)

References 30 publications

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“…At high coverage, the rectangular cell permits two molecules per cell, each with the C–Cl axis canted at roughly 18° to the surface normal; the orientation of the C–Cl bond vectors alternates between “up” (Cl away from the surface) and “down” (Cl toward the surface) between similarly aligned rows. This result was previously noted in MD simulation of CH 3 Cl adsorbed on Xe-coated graphite . At lower coverage, the C–Cl bond vectors are oriented nearly parallel to the surface, similar to the findings in this study and to the results of single-molecule MD simulation, although within the plane, the molecules appear to prefer a “zigzag” ferroelectric order that could not be identified in the present study.…”

Section: Resultssupporting

confidence: 91%

Multilayer Adsorption of Methane and Chloromethane on the Molybdenum (100) Surface

Tsige

2012

J. Phys. Chem. C

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Using all-atom molecular dynamics simulations, the multilayer adsorption of two single-carbon alkane analogues methane (CH 4 ) and chloromethane (CH 3 Cl)in the liquid phase on a metallic substrate (molybdenum (100) surface) has been studied to elucidate differences in the adsorbed film structure as a function of the overall film thickness, system temperature, substrate mobility, and pairwise substrate interaction potential (Lennard-Jones 12-6 versus embedded atom method versus Lennard-Jones 9-3 "wall" potential, used as a basis for comparison). Simulations suggest a clear predilection to well-ordered packing arrangements dictated by the adsorbate molecular geometry when adsorbed on the flat, featureless Lennard-Jones wall, but adsorption on the atomistic molybdenum substrate exhibits a more complex structure and orientation influenced by the adsorbate molecular geometry but also dependent on the presence or lack of small variations in surface structure caused by substrate mobility and interatomic potential. The result illustrates differences in packing geometry and surface binding energy on very noticeable scales despite the magnitude of surface vibrations allowed.

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Section: Resultssupporting

confidence: 91%

Multilayer Adsorption of Methane and Chloromethane on the Molybdenum (100) Surface

Tsige

2012

J. Phys. Chem. C

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“…There are numerous simulation studies, where graphite has been used to test modeling methodologies and interaction potentials in the context of physisorption by comparing simulation and experiment. These investigations include physisorbed noble gases, , small nonpolar − and polar molecules, and rather large and more complex adsorbates. − …”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulation of a Binary Hydrocarbon Mixture near an Adsorbing Wall: Benzene/n-Heptane on Graphite

Fodi

Hentschke

1998

Langmuir

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We perform molecular dynamics simulations of molecularly thin (≈4 nm), binary hydrocarbon films adsorbed on the basal plane of graphite. Specifically we study the structural, dynamic, and thermodynamic properties of liquid benzene/n-heptane mixtures for different mole fractions. The intra adsorbate and the adsorbate−substrate interactions are described using a phenomenological force field, which is carefully parameterized via the temperature dependence of the densities and diffusion coefficients of the pure bulk systems and their mixtures. The interaction with the graphite surface is parameterized by comparing experimental and calculated isosteric heats of adsorption. The foremost quantity, which we calculate, is the adsorption isotherm, i.e., the surface excess concentration as a function of the benzene bulk mole fraction, at T = 283 K. The latter, which is extremely sensitive to the parameterization, is in quite reasonable agreement with the experiment. Along with the isotherm we compare the surface-induced ordering of the two components in terms of order parameter profiles. In addition, the dynamical behavior of benzene on graphite at monolayer coverage is examined, including the experimentally observed liquid-to-( × )R19° solid transition.

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“…In recent years there has been considerable interest in the study of the structural and thermodynamic properties of adsorbed monolayers by computer simulation. − When used in combination with diffraction and calorimetric measurements, molecular dynamics (MD) has proved to be a particularly powerful technique. Monolayers of rare gases, especially krypton, on graphite have been investigated extensively , and these simulations have been extended to complicated adsorbates, such as small linear , polar, and tetrahedral molecules. , Recently, long-chain molecules, and alkanes in particular, have been the subject of considerable theoretical and experimental research, − due in part to the widespread application of scanning tunneling microscopy and other proximal probe techniques to study these adsorbates. The structural and orientational ordering of these alkane molecules physisorbed from solution onto various substrates is a topic of considerable interest. , There is a delicate balance between the energy associated with the flexibility of the chains, the molecule−surface energy, and the intermolecular interactions within the adsorbates which gives rise to a rich phase diagram and the appearance of new structures.…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulations of the Melting of a Hexane Monolayer: Isotropic versus Anisotropic Force Fields

Peters

Tildesley

1996

Langmuir

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Molecular dynamics simulations of a hexane monolayer on the basal-plane surface of graphite have been performed to investigate the effect of an anisotropic force field on the melting process. In two sets of simulations, which are carried out for a number of temperatures ranging from the solid to the fluid state of the monolayer, the molecules are described either by a skeletal model, where the interaction sites are represented by a "united atom" model, or by a model where the interaction sites are shifted away from the mass site (the "anisotropic united atom" model). Independent of the model, the low temperature configuration is an orientationally ordered herringbone structure, which on heating undergoes an orientational phase transition to a rectangular-centered structure where the molecules tend to align along one direction. The solid subsequently melts at approximately 175 K. However, the anisotropic force field promotes a perpendicular orientation of the backbone of the hexane molecules and, in contrast to the "united atom" model, molecules exhibit a smaller tilt and a lower percentage of gauche defects at melting. This is compensated by increased librational motion in the plane of the substrate.

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Structure of Physisorbed Overlayers of Dipolar Molecules: A Combined Study by Atomic-Beam Scattering and Molecular Dynamics

Cited by 55 publications

References 30 publications

Multilayer Adsorption of Methane and Chloromethane on the Molybdenum (100) Surface

Multilayer Adsorption of Methane and Chloromethane on the Molybdenum (100) Surface

Molecular Dynamics Simulation of a Binary Hydrocarbon Mixture near an Adsorbing Wall: Benzene/n-Heptane on Graphite

Molecular Dynamics Simulations of the Melting of a Hexane Monolayer: Isotropic versus Anisotropic Force Fields

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