2,542 research outputs found
An Analysis of the Quasicontinuum Method
The aim of this paper is to present a streamlined and fully three-dimensional
version of the quasicontinuum (QC) theory of Tadmor et al. and to analyze its
accuracy and convergence characteristics. Specifically, we assess the effect of
the summation rules on accuracy; we determine the rate of convergence of the
method in the presence of strong singularities, such as point loads; and we
assess the effect of the refinement tolerance, which controls the rate at which
new nodes are inserted in the model, on the development of dislocation
microstructures.Comment: 30 pages, 16 figures. To appear in Jornal of the Mechanics and
Physics of Solid
Negative specific heat in a Lennard-Jones-like gas with long-range interactions
We study, through molecular dynamics, a conservative two-dimensional
Lennard-Jones-like gas (with attractive potential ). We
consider the effect of the range index of interactions, number of
particles, total energy and particle density. We detect negative specific heat
when the interactions become long-ranged ().Comment: LaTeX, 8 pages, 4 eps figures, contributed paper to the Proceedings
of the International School and Workshop on Nonextensive Thermodynamics and
physical applications, NEXT 2001, 23-30 May 2001, Cagliari (Italy) (Physica
A) (New Title, new Fig. 4
Liquid State Anomalies for the Stell-Hemmer Core-Softened Potential
We study the Stell-Hemmer potential using both analytic (exact and
approximate ) solutions and numerical simulations. We observe in the
liquid phase an anomalous decrease in specific volume and isothermal
compressibility upon heating, and an anomalous increase in the diffusion
coefficient with pressure. We relate the anomalies to the existence of two
different local structures in the liquid phase. Our results are consistent with
the possibility of a low temperature/high pressure liquid-liquid phase
transition.Comment: 4 pages in one gzipped ps file including 11 figures; One RevTex and
11 gzipped eps figure
Recommended from our members
Poor choices: the limits of competitive markets in the provision of essential services to low-income consumers
A major study of the problems faced by the poor in the market for seven essential services in the UK - energy, food, housing, water, telecoms, transport, and financial services. Together these represent 60% of spending by the poorest 30% of households
Matter Wave Scattering and Guiding by Atomic Arrays
We investigate the possibility that linear arrays of atoms can guide matter
waves, much as fiber optics guide light. We model the atomic line as a quasi-1D
array of s wave point scatterers embedded in 2D. Our theoretical study reveals
how matter wave guiding arises from the interplay of scattering phenomena with
bands and conduction along the array. We discuss the conditions under which a
straight or curved array of atoms can guide a beam focused at one end of the
array.Comment: Submitted to Phys. Rev.
On the equation of state of a dense columnar liquid crystal
An accurate description of a columnar liquid crystal of hard disks at high
packing fractions is presented using an improved free-volume theory. It is
shown that the orientational entropy of the disks in the one-dimensional fluid
direction leads to a different high-density scaling pressure compared to the
prediction from traditional cell theory. Excellent quantitative agreement is
found with recent Monte-Carlo simulation results for various thermodynamic and
structural properties of the columnar state.Comment: 4 pages, 2 figures, to appear in Phys. Rev. Let
Parametrization of the Hybrid Potential for Pairs of Neutral Atoms
The hybrid form is a combination of the Rydberg potential and the London
inverse-sixth-power energy. It is accurate at all relevant distance scales and
simple enough for use in all-atom simulations of biomolecules. One may compute
the parameters of the hybrid potential for the ground state of a pair of
neutral atoms from their internuclear separation, the depth and curvature of
their potential at its minimum, and from their van der Waals coefficient of
dispersion.Comment: 7 pages, 11 figures, includes lithium, sodium, & potassium dimers,
minor correction
- …