Two- to three-dimensional cluster shape transition induced by a semi-infinite strained layer

2002 ◽  
Vol 65 (3) ◽  
Author(s):  
Cheng-Hsiao Lin ◽  
Yan-Chr Tsai
Keyword(s):  
Three Dimensional ◽  
Shape Transition ◽  
Strained Layer ◽  
Cluster Shape

scholarly journals Clusters Formed by Dumbbell-like One-Patch Particles Confined in Thin Systems

2021 ◽  
Author(s):  
Masahide Sato
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Particle Interaction ◽  
Three Dimensional ◽  
The Other ◽  
Spherical Particles ◽  
Dimensionless Distance ◽  
Large Island ◽  
Cluster Shape

Abstract Performing isothermal-isochoric Monte Carlo simulations, I examine the types of clusters that dumbbell-like one–patch particles form in thin space between two parallel walls, assuming that each particle is synthesized through the merging of two particles, one non-attracting and the other attracting for which, for example, the inter-particle interaction is approximated by the DLVO model. The shape of these dumbbell-like particles is controlled by the ratio of the diameters q of the two spherical particles and by the dimensionless distance l between them. Using a modified Kern–Frenkel potential, I examine the dependence of the cluster shape on l and q. Large island-like clusters are created when q < 1. With increasing q, the clusters become chain-like. When q increases further, elongated clusters and regular polygonal clusters are created. In hte simulations, the cluster shape becomes three-dimensional with increasing l because the thickness of the thin system increases proportionally to l.

scholarly journals Clusters formed by dumbbell-like one-patch particles confined in thin systems

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Masahide Sato
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Particle Interaction ◽  
Three Dimensional ◽  
The Other ◽  
Spherical Particles ◽  
Dimensionless Distance ◽  
Large Island ◽  
Cluster Shape

AbstractPerforming isothermal-isochoric Monte Carlo simulations, I examine the types of clusters that dumbbell-like one–patch particles form in thin space between two parallel walls, assuming that each particle is synthesized through the merging of two particles, one non-attracting and the other attracting for which, for example, the inter-particle interaction is approximated by the DLVO model . The shape of these dumbbell-like particles is controlled by the ratio of the diameters q of the two spherical particles and by the dimensionless distance l between these centers. Using a modified Kern–Frenkel potential, I examine the dependence of the cluster shape on l and q. Large island-like clusters are created when $$q<1$$ q < 1 . With increasing q, the clusters become chain-like . When q increases further, elongated clusters and regular polygonal clusters are created. In the simulations, the cluster shape becomes three-dimensional with increasing l because the thickness of the thin system increases proportionally to l.

GLOBAL GEOMETRY OPTIMIZATION OF SILICON CLUSTERS EMPLOYING EMPIRICAL POTENTIALS, DENSITY FUNCTIONALS, AND AB INITIO CALCULATIONS

2005 ◽  
Vol 04 (04) ◽  
pp. 1119-1151 ◽  
Author(s):  
ADEM TEKIN ◽  
BERND HARTKE
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Transition Region ◽  
Basis Set ◽  
Silicon Cluster ◽  
Shape Transition ◽  
Silicon Clusters ◽  
Empirical Potentials ◽  
Cluster Shape ◽  
Spherical Structures

Si n clusters in the size range n = 4–30 have been investigated using a combination of global structure optimization methods with DFT and ab initio calculations. One of the central aims is to provide explanations for the structural transition from prolate to spherical outer shapes at about n = 25, as observed in ion mobility measurements. Firstly, several existing empirical potentials for silicon and a newly generated variant of one of them were better adapted to small silicon clusters, by global optimization of their parameters. The best resulting empirical potentials were then employed in global cluster structure optimizations. The most promising structures from this stage were relaxed further at the DFT level with the hybrid B3LYP functional. For the resulting structures, single point energies have been calculated at the LMP2 level with a reasonable medium-sized basis set, cc-pVTZ. These DFT and LMP2 calculations were also carried out for the best structures proposed in the literature, including the most recent ones, to obtain the currently best and most complete overall picture of the structural preferences of silicon clusters. In agreement with recent findings, results obtained at the DFT level do support the shape transition from prolate to spherical structures, beginning with Si 26 (albeit not completely without problems). In stark contrast, at the LMP2 level, the dominance of spherical structures after the transition region could not be confirmed. Instead, just as below the transition region, prolate isomers are obtained as the lowest-energy structures for n ≤ 29. We conclude that higher (probably multireference) levels of theoretical treatments are needed before the puzzle of the silicon cluster shape transition at n = 25 can safely be considered as explained.

scholarly journals Shape transition of coherent three-dimensional (In,Ga)As islands on GaAs(100)

2001 ◽  
Vol 79 (25) ◽  
pp. 4219-4221 ◽  
Author(s):  
Wenquan Ma ◽  
Richard Nötzel ◽  
Hans-Peter Schönherr ◽  
Klaus H. Ploog
Keyword(s):  
Three Dimensional ◽  
Shape Transition

Phonon frequencies for Si-Ge strained-layer superlattices calculated in a three-dimensional model

1990 ◽  
Vol 42 (11) ◽  
pp. 7033-7041 ◽  
Author(s):  
R. A. Ghanbari ◽  
J. D. White ◽  
G. Fasol ◽  
C. J. Gibbings ◽  
C. G. Tuppen
Keyword(s):  
Three Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Strained Layer ◽  
Strained Layer Superlattices
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