نتایج جستجو برای: van der waals model

تعداد نتایج: 2290763  

1999
N. Westbrook C. I. Westbrook A. Landragin G. Labeyrie L. Cognet V. Savalli G. Horvath V. Bagnato

After a brief introduction to the Ðeld of atom optics and to atomic mirrors, we present experimental results obtained in our group during the last two years while studying the reÑection of rubidium atoms by an evanescent wave. These involve the Ðrst measurement of the van der Waals force between an atom in its ground state and a dielectric wall, as well as the demonstration of a reÑection grati...

Journal: :Physical review letters 2007
Vassilios Yannopapas Nikolay V Vitanov

We present a first-principles method for the determination of the van der Waals interactions for a collection of finite-sized macroscopic bodies. The method is based on fluctuational electrodynamics and a rigorous multiple-scattering method for the electromagnetic field. As such, the method takes fully into account retardation, many-body, multipolar, and near-fields effects. By application of t...

1999
J. S. Wettlaufer

The effect of impurities on the surface and interfacial melting of ice is investigated in the context of the Derjaguin-Landau-Verwey-Overbeek theory by calculating van der Waals and Coulombic interactions within interfacial solution films. At high temperatures, the classical solute effect dominates the melting behavior. However, depending on the amount of impurity, as temperature decreases the ...

2005
D. Kurfeß H. Hinrichsen

Fine powders often tend to agglomerate due to van der Waals forces between the particles. These forces can be reduced significantly by covering the particles with nanoscaled adsorbates, as shown by recent experiments. In the present work a quantitative statistical analysis of the effect of powder flow regulating nanomaterials on the adhesive forces in powders is given. Covering two spherical po...

Journal: :The Journal of chemical physics 2013
Anh D Phan Trinh X Hoang The-Long Phan Lilia M Woods

The van der Waals interaction between a lipid membrane and a substrate covered by a graphene sheet is investigated using the Lifshitz theory. The reflection coefficients are obtained for a layered planar system submerged in water. The dielectric response properties of the involved materials are also specified and discussed. Our calculations show that a graphene covered substrate can repel the b...

2011
Sabrina Disch Erik Wetterskog Raphaël P. Hermann German Salazar-Alvarez Peter Busch Thomas Brückel Lennart Bergström Saeed Kamali

Grazing incidence small-angle scattering and electron microscopy have been used to show for the first time that nonspherical nanoparticles can assemble into highly ordered body-centered tetragonal mesocrystals. Energy models accounting for the directionality and magnitude of the van der Waals and dipolar interactions as a function of the degree of truncation of the nanocubes illustrated the imp...

Journal: :Toxicology letters 1998
S Hameroff

1. A consensus view holds that anesthetics act by van der Waals forces in hydrophobic pockets of select brain proteins to ablate consciousness. 2. What is consciousness? Enigmatic features of consciousness (e.g. 'qualia', binding, non-computability, pre-conscious-->conscious transition, nondeterministic free will) may be explained by the occurrence of quantum coherent states in the brain. 3. Va...

Journal: :The Journal of chemical physics 2005
Svetla D Chakarova Elsebeth Schröder

Density functional theory is in principle exact and includes also long-range interactions, such as the van der Waals interactions. These are, however, part of the exchange-correlation energy functional that needs to be approximated, and are absent in the local and semilocal standard implementations. Recently a density functional which includes van der Waals interactions for planar systems has b...

Journal: :Journal of the American Chemical Society 2014
Tatyana E Shubina Dmitry I Sharapa Christina Schubert Dirk Zahn Marcus Halik Paul A Keller Stephen G Pyne Sreenu Jennepalli Dirk M Guldi Timothy Clark

Density functional theory calculations indicate that van der Waals fullerene dimers and larger oligomers can form interstitial electron traps in which the electrons are even more strongly bound than in isolated fullerene radical anions. The fullerenes behave like "super atoms", and the interstitial electron traps represent one-electron intermolecular σ-bonds. Spectroelectrochemical measurements...

2006
Christian Beck Michael C. Mackey

We argue that a recent discussion of Jetzer and Straumann [Phys. Lett. B 606, 77 (2005)] relating the measured noise spectrum in Josephson junctions to van der Waals forces is incorrect. The measured noise spectrum in Josephson junctions is a consequence of the fluctuation dissipation theorem and the Josephson effect and has nothing to do with van der Waals forces. Consequently, the argument of...

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