Mapping the global minima of binary Morse clusters: The effects of range mismatch

Calvo, F.; Yurtsever, E.

doi:10.1016/j.comptc.2013.05.014

Cited by 7 publications

(6 citation statements)

References 40 publications

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“…The aggregation of different types of particles is expected to increase the diversity of the arising structures. This has been observed in several binary systems and, in particular, when combining Morse clusters of different ranges . Conversely, we have shown that combining very short-ranged (e.g., ρ = 25 and ρ = 30) Morse potentials, having one of the components in excess, does not lead to binary clusters with significantly different global minimum structures .…”

Section: Results and Discussionsupporting

confidence: 51%

A Detailed Study on the Low-Energy Structures of Charged Colloidal Clusters

Cruz

Marques

2016

J. Phys. Chem. B

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The target of this investigation is the systematic characterization of the low-energy structures of charged colloidal clusters that may be important to understand the self-assembling process of biomolecules. The aggregation of charged colloidal particles is governed by the attractive short-ranged Morse potential and the Yukawa repulsive tail to describe the long-range charge effect. A global optimization strategy, based on our own evolutionary algorithm, was adopted to discover the low-energy structures of colloidal clusters composed of up to 20 particles. A detailed analysis of the low-energy structures involving charged particles shows that the appearance of the Bernal spiral as the most stable motif occurs, first, at N = 6, but it is favored for larger clusters (N ≥ 13); for 6 ≤ N ≤ 12, there is a competition between the spiral (which is favored for higher charges) and more spherical-like structures. Finally, we study binary clusters composed by two sets of differently charged colloidal particles. Although a great diversity of low-energy structures is observed (especially for aggregates with one of the components in excess), the global minimum is disputed by three structural motifs depending on the composition of the cluster and, in some cases, on the range of the Morse potential.

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Section: Results and Discussionsupporting

confidence: 51%

A Detailed Study on the Low-Energy Structures of Charged Colloidal Clusters

Cruz

Marques

2016

J. Phys. Chem. B

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“…As far as chemical order is now concerned, all clusters exhibit a clear core/shell phase separation, consistently with our previous analysis. 35 At the present size and composition, there are not enough B particles to coat the core of A particles completely, and several long-range particles are on the outside. The detailed chemical order is rather sensitive to the range, as illustrated by the two clusters with medium or short-range interactions [6;9] and [5.9;6.1], which share a common close-packed structure but slightly differ in the most stable homotop.…”

Section: A Binary Morse Clustersmentioning

confidence: 90%

“…Following previous works 34, 35 we set both D and r 0 to unity for all A-A, A-B, and B-B interactions, and a simple combination rule ρ AB = (ρ A + ρ B )/2 for the range of the mixed interaction, given the ranges ρ A and ρ B of the two alike pairs. The clusters are thus characterized by the pair of ranges, denoted as [ρ A ;ρ B ] with ρ A < ρ B , and chosen from the three series [ρ;12 − ρ] and [ρ;6] with ρ = 3, 3.5, 4, 4.5, 5, 5.5, 5.7, 5.9, as well as [6;ρ] with ρ = 6.1, 6.3, 6.5, 7, 7.5, 8, 8.5, 9. Relative to the LJ interaction that is equivalent to ρ = 6 and considered to be medium ranged, ranges lower (higher) than 6 will be denoted as long (short).…”

Section: A Binary Morse Clustersmentioning

confidence: 99%

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Evidence for broken ergodicity due to chemical alloying from the dissociation kinetics of binary clusters

Calvo

Yurtsever

2014

The Journal of Chemical Physics

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The interplay between thermal relaxation and statistical dissociation in binary Morse clusters (AB)N has been investigated using numerical simulations and simple statistical approaches, for a variety of interaction parameters covering miscible and non-miscible regimes. While all clusters exhibit a core/shell phase separation pattern in their most stable, T = 0 structure, different melting mechanisms are identified depending on the ranges and their mismatch, including two-step melting of the surface and the core or premelting as alloying. The preference for emitting A or B particles upon evaporation has been evaluated assuming that the cluster is either thermally equilibrated or vibrationally excited in its ground state structure, and compared to the predictions of the Weisskopf theory. The variations of the dissociation rate constants with increasing energy and the branching ratio between the two channels show significant differences in both cases, especially when the clusters are miscible and bound by short-range forces, which indicates that the time scale for evaporation is much shorter than the equilibration time. Our results suggest that dissociation properties could be used to test the ergodic hypothesis in such compounds.

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“…The possibility of fine-tuning their properties is enhanced when both size and composition are varied. However, the structural characterization, necessary for a precise understanding of their properties, becomes a problem, since the enormous amount of structural conformations of a pure cluster is significantly increased by the combinatorial possibilities of binary ones [1][2][3]. Therefore, the search for minimal energy configurations has to be approached following a strategy that i) insures the diversity of the local minimal energy conformations, that is, how many non-equivalent configurations are obtained as the two species are mixed; and, ii) balances reasonable computation times and the "certainty" of not loosing potentially important conformations.…”

Section: Introductionmentioning

confidence: 99%

Diversity Characterization of Binary Clusters by Means of a Generalized Distance

Ramírez

Rogan

Valdivia

et al. 2016

Zeitschrift Für Physikalische Chemie

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We characterize, by means of the definition of a generalized distance, the differences and similarities between binary nanoclusters. To define analytically, and to compute numerically this distance, we have generalized an original concept that was introduced for pure clusters. Since the diversity of cluster conformations grows exponentially with their size, and becomes even larger when the cluster atoms are of more than one species, we limit our attention to small ones. Thus, to illustrate and analyze our distance definition we characterize the Lennard-Jones (U) minimum energy conformations of two- and threedimensional (2D and 3D) binary clusters, for 5 <= N <= 12, where N is the number of atoms of the cluster. In addition, when varying the 1,1 potential parameters, we find that the number of minima decreases as the range of the potential of one of the species is increased, and confirm that minimal energy conformations adopt a well defined core-shell configuration.Fondo Nacional de Investigaciones Cientificas y Tecnologicas (FONDECYT, Chile) 1110135 1120399 1130272 Financiamiento Basal para Centres Cientificos y Tecnologicos de Excelencia (CEDENNA, Chile) FB080

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Mapping the global minima of binary Morse clusters: The effects of range mismatch

Cited by 7 publications

References 40 publications

A Detailed Study on the Low-Energy Structures of Charged Colloidal Clusters

A Detailed Study on the Low-Energy Structures of Charged Colloidal Clusters

Evidence for broken ergodicity due to chemical alloying from the dissociation kinetics of binary clusters

Diversity Characterization of Binary Clusters by Means of a Generalized Distance

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