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Chaudhuri P.,CNRS Physics Laboratory of Condensed Matter and Nanostructure | Berthier L.,Montpellier University | Sastry S.,Jawaharlal Nehru Centre for Advanced Scientific Research
Physical Review Letters | Year: 2010

We numerically produce fully amorphous assemblies of frictionless spheres in three dimensions and study the jamming transition these packings undergo at large volume fractions. We specify four protocols yielding a critical value for the jamming volume fraction which is sharply defined in the limit of large system size, but is different for each protocol. Thus, we directly establish the existence of a continuous range of volume fractions where nonequilibrium jamming transitions occur. However, these jamming transitions share the same critical behavior. Our results suggest that, even in the absence of partial crystalline ordering, a unique location of a random close packing does not exist. © 2010 The American Physical Society. Source

Bruneval F.,CEA Saclay Nuclear Research Center | Marques M.A.L.,University of Lyon | Marques M.A.L.,CNRS Physics Laboratory of Condensed Matter and Nanostructure
Journal of Chemical Theory and Computation | Year: 2013

The GW approximation is nowadays being used to obtain accurate quasiparticle energies of atoms and molecules. In practice, the GW approximation is generally evaluated perturbatively, based on a prior self-consistent calculation within a simpler approximation. The final result thus depends on the choice of the self-consistent mean-field chosen as a starting point. Using a recently developed GW code based on Gaussian basis functions, we benchmark a wide range of starting points for perturbative GW, including Hartree-Fock, LDA, PBE, PBE0, B3LYP, HSE06, BH&HLYP, CAM-B3LYP, and tuned CAM-B3LYP. In the evaluation of the ionization energy, the hybrid functionals are clearly superior results starting points when compared to Hartree-Fock, to LDA, or to the semilocal approximations. Furthermore, among the hybrid functionals, the ones with the highest proportion of exact-exchange usually perform best. Finally, the reliability of the frozen-core approximation, that allows for a considerable speed-up of the calculations, is demonstrated. © 2012 American Chemical Society. Source

Biance A.-L.,University Claude Bernard Lyon 1 | Biance A.-L.,CNRS Physics Laboratory of Condensed Matter and Nanostructure | Delbos A.,University Paris Est Creteil | Pitois O.,University Paris Est Creteil
Physical Review Letters | Year: 2011

The stability of foam is investigated experimentally through coalescence events. Instability (coalescence) occurs when the system is submitted to external perturbations (T1) and when the liquid amount in the film network is below a critical value. Microscopically, transient thick films are observed during film rearrangements. Film rupture, with coalescence and eventual collapse of the foam, occurs when the available local liquid amount is too small for transient films to be formed. Similar experiments and results are shown in the two-bubble case. © 2011 American Physical Society. Source

Joly L.,CNRS Physics Laboratory of Condensed Matter and Nanostructure
Journal of Chemical Physics | Year: 2011

This article discusses the way the standard description of capillary filling dynamics has to be modified to account for liquid/solid slip in nanometric pores. It focuses, in particular, on the case of a large slip length compared to the pore size. It is shown that the liquid viscosity does not play a role, and that the flow is only controlled by the friction coefficient of the liquid at the wall. Moreover, in the Washburn regime, the filling velocity does not depend on the tube radius. Finally, molecular dynamics simulations suggest that this standard description fails to describe the early stage of capillary filling of carbon nanotubes by water, since viscous dissipation at the tube entrance must be taken into account. © 2011 American Institute of Physics. Source

Tournus F.,CNRS Physics Laboratory of Condensed Matter and Nanostructure
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2011

Efforts are currently under way to produce nanoparticle samples with a size dispersion as low as possible, using deposition of preformed clusters on a substrate. However, even for diluted cluster films, contact or coalescence between neighboring clusters cannot be totally avoided due to the random nature of the deposition process. Consequently, the incident particle-size distribution will necessarily be degraded, with the statistical formation of multimers (dimers, trimers, or more generally nmers). In this article, we consider diluted assemblies of nanoparticles (with a narrow size distribution) randomly deposited on a surface and develop theoretical tools to assess the various multimer proportions. We establish simple and reliable analytical approximations of the probability for a cluster to form an nmer and the subsequent multimer proportion. These results can be applied in the analysis of experimental samples: They constitute a convenient tool for experimentalists in the design of their nanoparticle sample and the interpretation of experimental measurements. © 2011 American Physical Society. Source

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