266 research outputs found
Are defect models consistent with the entropy and specific heat of glass-formers?
We show that point-like defect model of glasses cannot explain thermodynamic
properties of glass-formers, as for example the excess specific heat close to
the glass transition, contrary to the claim of J.P. Garrahan, D. Chandler
[Proc. Natl. Acad. Sci. 100, 9710 (2003)]. More general models and approaches
in terms of extended defects are also discussed.Comment: 4 pages, version to appear in J. Chem. Phys with a Note Adde
Comment on ``Stripe Glasses: Self-Generated Randomness in a Uniformly Frustrated System''
comment on J. Schmalian and P. Wolynes, Phys. Rev. Lett. {\bf 85}, 836
(2000).Comment: 1 page, 1 Figure, accepted in Phys. Rev. Letter
Locally preferred structure in simple atomic liquids
We propose a method to determine the locally preferred structure of model
liquids. This latter is obtained numerically as the global minimum of the
effective energy surface of clusters formed by small numbers of particles
embedded in a liquid-like environment. The effective energy is the sum of the
intra-cluster interaction potential and of an external field that describes the
influence of the embedding bulk liquid at a mean-field level. Doing so we
minimize the surface effects present in isolated clusters without introducing
the full blown geometrical frustration present in bulk condensed phases. We
find that the locally preferred structure of the Lennard-Jones liquid is an
icosahedron, and that the liquid-like environment only slightly reduces the
relative stability of the icosahedral cluster. The influence of the boundary
conditions on the nature of the ground-state configuration of Lennard-Jones
clusters is also discussed.Comment: RevTeX 4, 17 pages, 6 eps figure
Aging and response properties in the parking-lot model
An adsorption-desorption (or parking-lot) model can reproduce qualitatively
the densification kinetics and other features of a weakly vibrated granular
material. Here we study the the two-time correlation and response functions of
the model and demonstrate that their behavior is consistent with recently
observed memory effects in granular materials. Although the densification
kinetics and hysteresis are robust properties, we show that the aging behavior
of the adsorption-desorption model is different from other models of granular
compaction. We propose an experimental test to distinguish the possible aging
behaviors.Comment: 9 pages, 7 figures, to appear in Eur. Phys. Jour.
- …