نتایج جستجو برای: van der waals model

تعداد نتایج: 2290763  

2001
Alexander I. Olemskoi

Within Tsallis’ nonextensive statistics, a model is elaborated to address self-similar time series as a thermodynamic system. Thermodynamic-type characteristics relevant to temperature, pressure, entropy, internal and free energies are introduced and tested. Stability conditions of time series analysis are discussed in details on the basis of Van der Waals model.

2001
N.F.A. van der Vegt F. Müller-Plathe A. Geleßus D. Johannsmann

Detailed atomistic molecular dynamics simulations were performed on monolayers of 4’-noctyl-4-cyanobiphenyl (8CB) adsorbed onto a surface of poly-m-alkanpyromellitimide (polym-APM), where m is the number of CH2 units between the imide moieties. Poly-3-APM and poly-4-APM surfaces served as model surfaces to investigate the influence of microscopic grooves, polar carbonyl groups exposed to the su...

2006
Lin Jin Yang-Xin Yu Guang-Hua Gao

To investigate globular protein–protein and protein–salt interactions in electrolyte solutions, a potential of mean force including hard-core repulsion, van der Waals attraction and electric double layer repulsion is proposed in this work. Both van der Waals attraction and double-layer repulsion are represented using hard spheres with two-Yukawa tails. The explicit analytical solution of osmoti...

Journal: :Physical review letters 2013
L Béguin A Vernier R Chicireanu T Lahaye A Browaeys

We report the direct measurement of the van der Waals interaction between two isolated, single Rydberg atoms separated by a controlled distance of a few micrometers. Working in a regime where the single-atom Rabi frequency for excitation to the Rydberg state is comparable to the interaction, we observe partial Rydberg blockade, whereby the time-dependent populations of the various two-atom stat...

1999
R. C. Forrey V. Kharchenko N. Balakrishnan A. Dalgarno

Vibrational relaxation of trapped molecules due to collisions with cold atoms is investigated using the results of quantum-mechanical scattering calculations. Trap loss is analyzed using an exactly solvable kinetic model that includes direct collisional quenching and an indirect process of vibrational predissociation. At low atom density, the relaxation is due primarily to collisional quenchin...

Journal: :Nanotechnology 2013
Till J W Wagner Dominic Vella

We present a theoretical investigation of stiction in nanoscale electromechanical contact switches. We develop a mathematical model to describe the deflection of a cantilever beam in response to both electrostatic and van der Waals forces. Particular focus is given to the question of whether adhesive van der Waals forces cause the cantilever to remain in the 'ON' state even when the electrostat...

Journal: :Journal of colloid and interface science 2014
Jaime C Hopkins Daniel M Dryden Wai-Yim Ching Roger H French V Adrian Parsegian Rudolf Podgornik

Small changes in the dielectric response of a material result in substantial variations in the Hamaker coefficient of the van der Waals interactions, as demonstrated in a simplified approximate model as well as a realistic example of amorphous silica with and without an exciton peak. Variation of the dielectric response spectra at one particular frequency influences all terms in the Matsubara s...

1997
U Ritschel M Gerwinski

Using field-theoretical methods and exploiting conformal invari-ance, we study Casimir forces at tricritical points exerted by long-range fluctuations of the order-parameter field. Special attention is paid to the situation where the symmetry is broken by the boundary conditions (extraordinary transition). Besides the parallel-plate configuration, we also discuss the geometries of two separate ...

Journal: :Nature communications 2013
Van Duc Nguyen Suzanne Faber Zhibing Hu Gerard H Wegdam Peter Schall

The critical Casimir force provides a thermodynamic analogue of the quantum mechanical Casimir force that arises from the confinement of electromagnetic field fluctuations. In its thermodynamic analogue, two surfaces immersed in a critical solvent mixture attract each other due to confinement of solvent concentration fluctuations. Here, we demonstrate the active assembly control of colloidal eq...

Journal: :The Journal of chemical physics 2005
Swaroop Chatterjee Henry S Ashbaugh Pablo G Debenedetti

We investigate the effect of adding nonpolar solutes at atmospheric pressure on water's temperature of maximum density, isothermal compressibility, and isobaric heat capacity, using a statistical mechanical model of water solutions [H. S. Ashbaugh, T. M. Truskett, and P. G. Debenedetti, J. Chem. Phys. 116, 2907 (2002)]. We find that the temperature of maximum density increases with solute hydro...

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