نتایج جستجو برای: van der waals behavior

تعداد نتایج: 816962  

Journal: :Physical review letters 2014
D Drosdoff Lilia M Woods

The van der Waals dispersion force between graphene nanoribbons is investigated. For this purpose, a nonretarded Lifshitz-like formula for parallel 1D systems is presented within the random phase approximation. Using the response properties of the ribbons from a tight binding model, it is found that the qualitative behavior of the force is similar to the one between two insulating 1D systems. O...

Journal: :Biophysical chemistry 2004
Yang Su Emilio Gallicchio

The non-polar component of the potential of mean force of dimerization of alanine dipeptide has been calculated in explicit solvent by free energy perturbation. We observe that the calculated PMF is inconsistent with a non-polar hydration free energy model based solely on the solute surface area. The non-linear behavior of the solute-solvent van der Waals energy is primarily responsible for the...

2004
J. Soto M. Becucci E. Castellucci

The aniline–neon van der Waals complex has been investigated from a theoretical point of view. The intermolecular distance, structure and rotational constants in the ground electronic state have been obtained by ab initio calculations using second-order Møller–Plesset (MP2) theory. The potential energy surface has also been determined. It has been found that two conformers exist: the anti, wher...

Journal: :The Journal of chemical physics 2006
S N Yaliraki Gabriel Longo Ella Gale I Szleifer Mark A Ratner

Recent single molecule experiments rely on the self-assembly of binary mixtures of molecules with very different properties in a stable monolayer, in order to probe the characteristics of the interspersed molecule of interest in a controlled environment. However, not all efforts at coassembly have been successful. To study systematically the behavior of such systems, we derive the free energy o...

2004
I V Bondarev Ph Lambin

Using a unified macroscopic QED formalism, we derive an integral equation for the van der Waals energy of a two-level atomic system near a carbon nanotube. The equation is valid for both strong and weak atom-vacuum-field coupling. By solving it numerically, we demonstrate the inapplicability of weak-coupling-based van der Waals interaction models in a close vicinity of the nanotube surface.

Journal: :The journal of physical chemistry. B 2006
Jaehun Chun Je-Luen Li Roberto Car Ilhan A Aksay Dudley A Saville

Orientational order of surfactant micelles and proteins on crystalline templates has been observed but, given that the template unit cell is significantly smaller than the characteristic size of the adsorbate, this order cannot be attributed to lattice epitaxy. We interpret the template-directed orientation of rodlike molecular assemblies as arising from anisotropic van der Waals interactions b...

Journal: :The Journal of chemical physics 2009
Poul Georg Moses Jens J Mortensen Bengt I Lundqvist Jens K Norskov

Accurate calculations of adsorption energies of cyclic molecules are of key importance in investigations of, e.g., hydrodesulfurization (HDS) catalysis. The present density functional theory (DFT) study of a set of important reactants, products, and inhibitors in HDS catalysis demonstrates that van der Waals interactions are essential for binding energies on MoS(2) surfaces and that DFT with a ...

2013
Santiago Alvarez

The distribution of distances from atoms of a particular element E to a probe atom X (oxygen in most cases), both bonded and intermolecular non-bonded contacts, has been analyzed. In general, the distribution is characterized by a maximum at short E⋯X distances corresponding to chemical bonds, followed by a range of unpopulated distances – the van der Waals gap – and a second maximum at longer ...

Journal: :Physical review. E, Statistical, nonlinear, and soft matter physics 2003
F P A Cortat S J Miklavcic

Through a study of the van der Waals interaction between a solid and an air-water interface, we investigate the practical and fundamental problem of the limiting height at which an object can approach a free surface. A numerical study of the interface shape reveals dependencies governed by two disparate length scales associated with the relative strengths of the van der Waals and bouyancy force...

2012
Yuka Nakano Yasuo Watanabe Yoshihiko Ito Shizuo Yamada Hiroaki Tokiwa

We propose a theoretical novel homodimer model of the β- adrenergic receptor (βAR) in complex with a heterogeneous mixture of free fatty acids (FFAs) and cholesterol based on first-principles calculations. We used the density-functional-based tight binding with dispersion (DFTB-D) method, which accurately evaluates van der Waals interactions between FFAs and amino acid residues in the receptor....

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