119 research outputs found
Continuum random sequential adsorption of polymer on a flat and homogeneous surface
Random sequential adsorption (RSA) of polymer, modeled as a chain of
identical spheres, is systematically studied. In order to control precisely
anisotropy and number of degrees of freedom, two different kinds of polymers
are used. In the first one, monomers are placed along a straight line, whereas
in the second, relative orientations of particles are random. Such polymers
fill a flat homogeneous surface randomly. The paper focuses on maximal random
coverage ratio and adsorption kinetics dependence on polymer size, shape
anisotropy, and numbers of degrees of freedom. Obtained results were discussed
and compared with other numerical experiments and theoretical predictions.Comment: 13 pages, 7 figure
Properties of random sequential adsorption of generalized dimers
Saturated random packing of particles built of two identical, relatively
shifted spheres in two and three dimensional flat and homogeneous space was
studied numerically using random sequential adsorption algorithm. The shift
between centers of spheres varied from 0.0 to 8.0 sphere diameters. Numerical
simulations allowed determine random sequential adsorption kinetics, saturated
random coverage ratio as well as available surface function and density
autocorrelation function.Comment: 5 pages, 8 figure
Scaling properties of the number of random sequential adsorption iterations needed to generate saturated random packing
The properties of the number of iterations in random sequential adsorption
protocol needed to generate finite saturated random packing of spherically
symmetric shapes were studied. Numerical results obtained for one, two, and
three dimensional packings were supported by analytical calculations valid for
any dimension . It has been shown that the number of iterations needed to
generate finite saturated packing is subject to Pareto distribution with
exponent and the median of this distribution scales with packing size
according to the power-law characterized by exponent . Obtained resultscan
be used in designing effective RSA simulations.Comment: 7 pages, 3 figure
Random packing of regular polygons and star polygons on a flat two-dimensional surface
Random packing of unoriented regular polygons and star polygons on a
two-dimensional flat, continuous surface is studied numerically using random
sequential adsorption algorithm. Obtained results are analyzed to determine
saturated random packing ratio as well as its density autocorrelation function.
Additionally, the kinetics of packing growth and available surface function are
measured. In general, stars give lower packing ratios than polygons, but, when
the number of vertexes is large enough, both shapes approach disks and,
therefore, properties of their packing reproduce already known results for
disks.Comment: 5 pages, 8 figure
Domain structure created by irreversible adsorption of dimers
Structure of monolayers built during adsorption process is strongly related
to the properties of adsorbed particles. The most important factor is their
shape. For example, adsorption of elongated molecules on patterned surfaces may
produce certain orientational order inside a covering layer. This study,
however, focuses on random adsorption of dimers on flat, homogeneous surfaces.
It has been observed that despite the lack of global orientational ordering,
adsorbed dimers may form local, orientationally ordered structures [1, 2]. Our
investigations focus on the dependence between domain size distribution and
environmental parameters such as ionic strength, which affects the range of
electrostatic interaction between molecules.Comment: 8 pages, 5 figures, Presented at the XXV Marian Smoluchowski
Symposium on Statistical Physics, Krak\'ow, Poland, September, 201
Random sequential adsorption of trimers and hexamers
Adsorption of trimers and hexamers built of identical spheres was studied
numerically using the Random Sequential Adsorption (RSA) algorithm. Particles
were adsorbed on a two dimensional, flat and homogeneous surface. Numerical
simulations allow to establish the maximal random coverage ratio, RSA kinetics
as well as the Available Surface Function (ASF), which is crucial for
determining kinetics of the adsorption process obtained experimentally.
Additionally, the density autocorrelation function was measured. All the
results were compared with previous results obtained for spheres, dimers and
tetramers.Comment: 11 pages, 6 figure
Boundary conditions in random sequential adsorption
The influence of different boundary conditions on the density of random
packings of disks is studied. Packings are generated using the random
sequential adsorption algorithm with three different types of boundary
conditions: periodic, open, and wall. It is found that the finite size effects
are smallest for periodic boundary conditions, as expected. On the other hand,
in the case of open and wall boundaries it is possible to introduce an
effective packing size and a constant correction term to significantly improve
the packing densities.Comment: 9 pages, 7 figure
Multimodal stationary states under Cauchy noise
A L\'evy noise is an efficient description of out-of-equilibrium systems. The
presence of L\'evy flights results in a plenitude of noise-induced phenomena.
Among others, L\'evy flights can produce stationary states with more than one
modal value in single-well potentials. Here, we explore stationary states in
special double-well potentials demonstrating that a sufficiently high potential
barrier separating potential wells can produce bimodal stationary states in
each potential well. Furthermore, we explore how the decrease in the barrier
height affects the multimodality of stationary states. Finally, we explore a
role of the multimodality of stationary states on the noise induced escape over
the static potential barrier.Comment: 10 pages, 11 figure
Shapes for maximal coverage for two-dimensional random sequential adsorption
The random sequential adsorption of various particle shapes is studied in
order to determine the influence of particle anisotropy on the saturated random
packing. For all tested particles there is an optimal level of anisotropy which
maximizes the saturated packing fraction. It is found that a concave shape
derived from a dimer of disks gives a packing fraction of 0.5833, which is
comparable to the maximum packing fraction of ellipsoids and spherocylinders
and higher than any other studied shape. Discussion why this shape is so
beneficial for random sequential adsorption is given.Comment: 6 pages, 8 figures, 3 table
Noise-induced synchronization in the Fahy-Hamann model
We study the noise-induced synchronization in a system of particles moving in Fahy–Hamann potential [S. Fahy, D.R. Hamann,Phys.Rev.Lett. 69, 761 (1992)] and subjected to generalized Langevin forces. We investi- gate the synchronization dependence on system’s parameters and on mem- ory range. The results show that while in general memory acts against synchronization, for intermediate memory ranges the opposite effect can be observed. Generally the synchronization transition is found to depend on memory range, temperature and dissipation in the system. PAC
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