6 research outputs found
Eden growth model for aggregation of charged particles
The stochastic Eden model of charged particles aggregation in two-dimensional
systems is presented. This model is governed by two parameters: screening
length of electrostatic interaction, , and short range attraction
energy, . Different patterns of finite and infinite aggregates are observed.
They are of following types of morphologies: linear or linear with bending,
warm-like, DBM (dense-branching morphology), DBM with nucleus, and compact
Eden-like. The transition between the different modes of growth is studied and
phase diagram of the growth structures is obtained in
co-ordinates. The detailed aggregate structure analysis, including analysis of
their fractal properties, is presented. The scheme of the internal
inhomogeneous structure of aggregates is proposed.Comment: Revtex, 9 pages with 12 postscript figure
Percolation of the aligned dimers on a square lattice
Percolation and jamming phenomena are investigated for anisotropic sequential
deposition of dimers (particles occupying two adjacent adsorption sites) on a
square lattice. The influence of dimer alignment on the electrical conductivity
was examined. The percolation threshold for deposition of dimers was lower than
for deposition of monomers. Nevertheless, the problem belongs to the
universality class of random percolation. The lowest percolation threshold (pc
= 0.562) was observed for isotropic orientation of dimers. It was higher (pc =
0.586) in the case of dimers aligned strictly along one direction. The state of
dimer orientation influenced the concentration dependence of electrical
conductivity. The proposed model seems to be useful for description of the
percolating properties of anisotropic conductors.Comment: 6 pages, 9 figures, submitted to EPJ
Deterministic growth model of Laplacian charged particle aggregates
The results of the computer simulation of the aggregates growth of the
similarly charged particles in the framework of deterministic Laplacian growth
model on a square lattice are presented. Cluster growth is controlled by three
parameters , where - Laplacian growth parameter, -
energy of a particle sticking to a cluster, - the screening length of
electrostatic interactions. The phase diagram of cluster growth is built in the
co-ordinates . The zones of different cluster morphology are
selected: I-the zone of finite X-like structures,II-the zone of infinite
ramified structures, controlled by electrostatic interactions, III-the zone of
infinite structures with electrostatic interactions effectively switched off.
Simple electrostatic estimations of the locations of the zone boundaries are
presented. It is shown that in general case within the zone II the continuous
change of , controlled by parameters , takes place. In the
degeneration limit when the given model transforms into deterministic version
of the Eden model (at ), the crossover from linear to compact
structures is observed when passing through the boundary between the
zones I and II.Comment: REVTEX, 3 pages with 4 postscript figure
How the geometry makes the criticality in two - component spreading phenomena?
We study numerically a two-component A-B spreading model (SMK model) for
concave and convex radial growth of 2d-geometries. The seed is chosen to be an
occupied circle line, and growth spreads inside the circle (concave geometry)
or outside the circle (convex geometry). On the basis of generalised
diffusion-annihilation equation for domain evolution, we derive the mean field
relations describing quite well the results of numerical investigations. We
conclude that the intrinsic universality of the SMK does not depend on the
geometry and the dependence of criticality versus the curvature observed in
numerical experiments is only an apparent effect. We discuss the dependence of
the apparent critical exponent upon the spreading geometry and
initial conditions.Comment: Uses iopart.cls, 11 pages with 8 postscript figures embedde