High intensity tapping regime in a frustrated lattice gas model of granular compaction

In the frame of a well established lattice gas model for granular compaction, we investigate the high intensity tapping regime where a pile expands significantly during external excitation. We find that this model shows the same general trends as more sophisticated models based on molecular dynamic type simulations. In particular, a minimum in packing fraction as a function of tapping strength is observed in the reversible branch of an annealed tapping protocol.Comment: 5 pages, 4 figure

Uptake of gases in bundles of carbon nanotubes

Model calculations are presented which predict whether or not an arbitrary gas experiences significant absorption within carbon nanotubes and/or bundles of nanotubes. The potentials used in these calculations assume a conventional form, based on a sum of two-body interactions with individual carbon atoms; the latter employ energy and distance parameters which are derived from empirical combining rules. The results confirm intuitive expectation that small atoms and molecules are absorbed within both the interstitial channels and the tubes, while large atoms and molecules are absorbed almost exclusively within the tubes.Comment: 9 pages, 12 figures, submitted to PRB Newer version (8MAR2K). There was an error in the old one (23JAN2K). Please download thi

The Role of Power-Law Correlated Disorder in the Anderson Metal-Insulator Transition

We study the influence of scale-free correlated disorder on the metal-insulator transition in the Anderson model of localization. We use standard transfer matrix calculations and perform finite-size scaling of the largest inverse Lyapunov exponent to obtain the localization length for respective 3D tight-binding systems. The density of states is obtained from the full spectrum of eigenenergies of the Anderson Hamiltonian. We discuss the phase diagram of the metal-insulator transition and the influence of the correlated disorder on the critical exponents.Comment: 6 pages, 3 figure

Effect of Interaction Energies on the Adsorption of Glycine onto a Cu(110) Surface: A Monte Carlo Simulation

The purpose of the present work was to study the effect of the adsorbate–adsorbate interaction energy for the glycine/Cu(110) system using a Monte Carlo simulation in the grand canonical ensemble. The dependence of the surface pattern structures upon the temperature and diffusion rate was studied. For either reversible or irreversible adsorption, the results showed that it is possible to obtain condensed phases with a large degree of correlation for high diffusion rates and temperatures. Depending on the set of interaction energies for nearest- and next-nearest-neighbour molecules, these patterns form either hetero- or homo-chiral footprint domains. The results obtained are qualitatively consistent with the experimental pattern observed by other authors and allow an interpretation of the different proposed theoretical models used to explain experimental data

Frequency–amplitude behavior in the incipient movement of grains under vibration

International audienceThe onset of the movement of particles placed on a horizontal rough surface subject to a vertical sinusoidal vibration is investigated through tracking experiments, theoretical analysis, and numerical simulations. The frequency of vibration needed to move particles decays exponentially with the amplitude of the oscillatory input. This behavior is explained through a simple mechanism in which a forced damped harmonic oscillator with a spring constant represents all the interactions between the particle and the surface. The numerical results compare well with experimental data, demonstrating that the forces included in the numerical calculations suitably account for the main particle response, even though the complexity of the surface is not fully taken into account. Describing the way in which frequency varies with amplitude could be relevant to technological applications such as cleaning of material surfaces

On the dynamics of a liquid bridge between a sphere and a vertically vibrated solid surface

This work presents an experimental study of the response of a liquid bridge formed between a sphere and a plane solid surface subjected to a vertical sinusoidal vibration. The amplitude and frequency of the oscillations can be varied. The successive movement of the particle along with the bridge deformation is registered to follow the dynamics of the system. The motivation is to figure out how capillary and viscosity forces can be modeled with the help of the experimental data obtained and to settle down a simplified theoretical approach capable of being implemented in the description of many phenomena involving wet granular grains. The results indicate that the viscosity effects can be neglected as soon as the amplitude of the movement is not too small, still obtaining a reasonable description of the dynamical behavior of the sphere/liquid-bridge system

On the dynamics of a liquid bridge between a sphere and a vertically vibrated solid surface

This work presents an experimental study of the response of a liquid bridge formed between a sphere and a plane solid surface subjected to a vertical sinusoidal vibration. The amplitude and frequency of the oscillations can be varied. The successive movement of the particle along with the bridge deformation is registered to follow the dynamics of the system. The motivation is to figure out how capillary and viscosity forces can be modeled with the help of the experimental data obtained and to settle down a simplified theoretical approach capable of being implemented in the description of many phenomena involving wet granular grains. The results indicate that the viscosity effects can be neglected as soon as the amplitude of the movement is not too small, still obtaining a reasonable description of the dynamical behavior of the sphere/liquid-bridge system