88 research outputs found
Premelting-Induced Smoothening of the Ice-Vapor Interface
We perform computer simulations of the quasiliquid layer of ice formed at the
ice-vapor interface close to the ice Ih-liquid-vapor triple point of water. Our
study shows that the two distinct surfaces bounding the film behave at small
wavelengths as atomically rough and independent ice-water and water-vapor
interfaces. For long wavelengths, however, the two surfaces couple, large scale
parallel fluctuations are inhibited, and the ice-vapor interface becomes
smooth. Our results could help explain the complex morphology of ice
crystallites.Comment: postprint plus supplemental material with details on simulation and
theor
Disjoining Pressure and the Film-Height-Dependent Surface Tension of Thin Liquid Films: New Insight from Capillary Wave Fluctuations
In this paper we review simulation and experimental studies of thermal
capillary wave fluctuations as an ideal means for probing the underlying
disjoining pressure and surface tensions, and more generally, fine details of
the Interfacial Hamiltonian Model. We discuss recent simulation results that
reveal a film-height-dependent surface tension not accounted for in the
classical Interfacial Hamiltonian Model. We show how this observation may be
explained bottom-up from sound principles of statistical thermodynamics and
discuss some of its implications.Comment: File is accepted version with 70 pages and 13 figures. Submitted
23/08/2013; Accepted 06/11/2013; Online 17/11/201
Structure and fluctuations of the premelted liquid film of ice at the triple point
In this paper we study the structure of the ice/vapor interface in the neighborhood of the triple point for the TIP4P/2005 model. We probe the fluctuations of the ice/film and film/vapor surfaces that separate the liquid film from the coexisting bulk phases at basal, primary prismatic and secondary prismatic planes. The results are interpreted using a coupled sine Gordon plus Interface Hamiltonian model. At large length-scales, the two bounding surfaces are correlated and behave as a single complex ice/vapor interface. For small length, on the contrary, the ice/film and film/vapor surfaces behave very much like independent ice/water and water/vapor interfaces. The study suggests that the basal facet of the TIP4P/2005 model is smooth, the prismatic facet is close to a roughening transition, and the secondary prismatic facet is rough. For the faceted basal face, our fluctuation analysis allows us to estimate the step free energy in good agreement with experiment. Our results allow for a quantitative characterization of the extent to which the adsorbed quasi-liquid layer behaves as water, and explains experimental observations which reveal similar activation energies for crystals grown in bulk vapor or bulk water
Semi-infinite boundary conditions for the simulation of interfaces: The Ar/CO2(s) model revisited
We propose a method to account for the long tail corrections of dispersive forces in inhomogeneous systems. This method deals separately with the two interfaces that are usually present in a simulation setup, effectively establishing semi-infinite boundary conditions that are appropriate for the study of the interface between two infinite bulk phases. Using the wandering interface method, we calculate surface free energies of vapor–liquid, wall–liquid, and wall–vapor interfaces for a model of Lennard– Jones argon adsorbed on solid carbon dioxide. The results are employed as input to Young’s equation, and the wetting temperature located. This estimate is compared with predictions from the method of effective interface potentials and good agreement is found. Our results show that truncating Ar–Ar interactions at two and a half molecular diameters results in a dramatic decrease of the wetting temperature of about 40%.We would like to thank Marcus Müller for suggesting us to describe the cutoff dependence of wetting properties by means of the sharp-kink approximation (cf., Sec. V). We also benefitted from helpful discussions with P. Bryk, A. Archer, and E. de Miguel. Generous financial support of Ministerio de Educacion y Ciencia through Project Nos. FIS2010- 22047-C05-05 and FIS2010-14866; Comunidad Autónoma de Madrid through Project No. MODELICO-P2009/ESP- 1691; and Junta de AndalucÃa through Project No. P07- FQM02884 is gratefully acknowledged
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