21,782 research outputs found
Crystallography on Curved Surfaces
We study static and dynamical properties that distinguish two dimensional
crystals constrained to lie on a curved substrate from their flat space
counterparts. A generic mechanism of dislocation unbinding in the presence of
varying Gaussian curvature is presented in the context of a model surface
amenable to full analytical treatment. We find that glide diffusion of isolated
dislocations is suppressed by a binding potential of purely geometrical origin.
Finally, the energetics and biased diffusion dynamics of point defects such as
vacancies and interstitials is explained in terms of their geometric potential.Comment: 12 Pages, 8 Figure
Wetting of Curved Surfaces
As a first step towards a microscopic understanding of the effective
interaction between colloidal particles suspended in a solvent we study the
wetting behavior of one-component fluids at spheres and fibers. We describe
these phenomena within density functional theory which keeps track of the
microscopic interaction potentials governing these systems. In particular we
properly take into account the power-law decay of both the fluid-fluid
interaction potentials and the substrate potentials. The thicknesses of the
wetting films as a function of temperature and chemical potential as well as
the wetting phase diagrams are determined by minimizing an effective interface
potential which we obtain by applying a sharp-kink approximation to the density
functional. We compare our results with previous approaches to this problem.Comment: 54 pages, 17 figures, accepted for publication in Physica
Depletion forces near curved surfaces
Based on density functional theory the influence of curvature on the
depletion potential of a single big hard sphere immersed in a fluid of small
hard spheres with packing fraction \eta_s either inside or outside of a hard
spherical cavity of radius R_c is calculated. The relevant features of this
potential are analyzed as function of \eta_s and R_c. There is a very slow
convergence towards the flat wall limit R_c \to \infty. Our results allow us to
discuss the strength of depletion forces acting near membranes both in normal
and lateral directions and to make contact with recent experimental results
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