Structure and energetics of equiatomic K–Cs and Rb–Cs binary clusters

Hristova, Elisaveta; Grigoryan, Valeri G.; Springborg, Michael

doi:10.1063/1.2944244

Cited by 20 publications

(8 citation statements)

References 52 publications

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“…The similarity function (S) 35 between two different structures is also used to reveal the structural characteristics of Cu 38 at different temperatures.where N is the cluster size (N = 38) and R 0 is the geometrical center of the cluster (, and R i is the position vector of the ith atom), and r n (r′ n ) is the distance from the nth atom to the geometrical center of the cluster. For a given cluster all the distances are sorted in increasing order.…”

Section: Methodsmentioning

confidence: 99%

Static and dynamical isomerization of Cu38 cluster

Zhang

Duan

et al. 2019

Sci Rep

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The lowest-energy geometrical and electronic structures of Cu 38 cluster are investigated by density-functional calculations combined with a genetic algorithm based on a many body semi-empirical interatomic potential, the traditional FCC-truncated Octahedron (OH) and an incomplete-Mackay icosahedron (IMI) are recognized as the two lowest energy structures (energetically degenerate isomers) but with different electronic structures: a semiconductor-type with the energy-gap of 0.356 eV for the IMI and a metallic-type with negligible gap for the OH, which is in good agreement with the experimental results. The electron affinity and ionization potential of Cu 38 are also discussed and compared with the observations of the ultraviolet photoelectron spectroscopy experiments. The dynamical isomerization of the OH-like and IMI-like structures of Cu 38 is revealed to dominate the pre-melting stage through the investigation by the molecular dynamics annealing simulations.

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Section: Methodsmentioning

confidence: 99%

Static and dynamical isomerization of Cu38 cluster

Zhang

Duan

et al. 2019

Sci Rep

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“…We notice that neither sodium nor lithium pure clusters have a strong tendency to form amorphous structures, 67 so the amorphization of Li-Na nanoalloys is a synergistic effect, which results from a size mismatch which is slightly smaller than needed for a perfect pIh packing. Figure 7 shows the partial electronic densities of states (PDOS) for both ordered and disordered isomers of Na 19 K 36 and Li 19 Na 36 . The DOS has been obtained by broadening the KS eigenvalues with gaussian functions of width 0.06 eV.…”

Section: Stability Trends In Binary Alkali Nanoalloysmentioning

confidence: 99%

Identifying structural and energetic trends in isovalent core-shell nanoalloys as a function of composition and size mismatch

Aguado

López²

2011

The Journal of Chemical Physics

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We locate the putative global minimum structures of Na x Cs 55−x and Li x Cs 55−x nanoalloys through combined empirical potential and density functional theory calculations, and compare them to the structures of 55-atom Li-Na and Na-K nanoalloys obtained in a recent paper [A. Aguado and J. M. López, J. Chem. Phys. 133, 094302 (2010)]. Alkali nanoalloys are representative of isovalent metallic mixtures with a strong tendency towards core-shell segregation, and span a wide range of size mismatches. By comparing the four systems, we analyse how the size mismatch and composition affect the structures and relative stabilities of these mixtures, and identify useful generic trends. The Na-K system is found to possess a nearly optimal size mismatch for the formation of poly-icosahedral (pIh) structures with little strain. In systems with a larger size mismatch (Na-Cs and Li-Cs), frustration of the pIh packing induces for some compositions a reconstruction of the core, which adopts instead a decahedral packing. When the size mismatch is smaller than optimal (Li-Na), frustration leads to a partial amorphization of the structures. The excess energies are negative for all systems except for a few compositions, demonstrating that the four mixtures are reactive. Moreover, we find that Li-Cs and Li-Na mixtures are more reactive (i.e., they have more negative excess energies) than Na-K and Na-Cs mixtures, so the stability trends when comparing the different materials are exactly opposite to the trends observed in the bulk limit: the strongly non-reactive Li-alkali bulk mixtures become the most reactive ones at the nanoscale. For each material, we identify the magic composition x m which minimizes the excess energy. x m is found to increase with the size mismatch due to steric crowding effects, and for Li x Cs 55−x the most stable cluster has almost equiatomic composition. We advance a simple geometric packing rule that suffices to systematize all the observed trends in systems with large size mismatch (Na-K, Na-Cs, and Li-Cs). As the size mismatch is reduced, however, electron shell effects become more and more important and contribute significantly to the stability of the Li-Na system.

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“…The similarity function is employed to identify structural similarities, and it approaches 1 (0) if the two clusters are absolutely similar (different). 44 When comparing the Pt m Co n bimetallic clusters with the Pt N and Co N ones, the calculated results are basically the same owing to the identical shape of Pt N and Co N clusters. However, subtle differences between Figure 7a,b Note that the similarity functions of the 13-atom and 55atom sequences are larger than 95 and 98%, respectively.…”

Section: ■ Results and Discussionmentioning

confidence: 68%

“…The similarity function is employed to identify structural similarities, and it approaches 1 (0) if the two clusters are absolutely similar (different) …”

Section: Resultsmentioning

confidence: 99%

Basin Hopping Genetic Algorithm for Global Optimization of PtCo Clusters

Huang

et al. 2020

J. Chem. Inf. Model.

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In general, searching the lowest-energy structures is considerably more time-consuming for bimetallic clusters than for monometallic ones because of the presence of an increasing number of homotops and geometrical isomers. In this article, a basin hopping genetic algorithm (BHGA), in which the genetic algorithm is implanted into the basin hopping (BH) method, is proposed to search the lowest-energy structures of 13-, 38-, and 55-atom PtCo bimetallic clusters. The results reveal that the proposed BHGA, as compared with the standard BH method, can markedly improve the convergent speed for global optimization and the possibility for finding the global minima on the potential energy surface. Meanwhile, referencing the monometallic structures in initializations may further raise the searching efficiency. For all the optimized clusters, both the excess energy and the second difference of the energy are calculated to examine their relative stabilities at different atomic ratios. The bond order parameter, the similarity function, and the shape factor are also adopted to quantitatively characterize the cluster structures. The results indicate that the 13- and the 55-atom systems tend to be icosahedral despite different degrees of lattice distortions. In contrast, for the 38-atom system, Pt10Co28, Pt11Co27, Pt17Co21, Pt19Co19, Pt20Co18, and Pt30Co8 tend to be disordered, while Pt21Co17 presents a defected face-centered cubic (fcc) structure, and the remaining clusters are perfect fcc. The methodology and results of this work have referential significance to the exploration of other alloy clusters.

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Structure and energetics of equiatomic K–Cs and Rb–Cs binary clusters

Cited by 20 publications

References 52 publications

Static and dynamical isomerization of Cu38 cluster

Static and dynamical isomerization of Cu38 cluster

Identifying structural and energetic trends in isovalent core-shell nanoalloys as a function of composition and size mismatch

Basin Hopping Genetic Algorithm for Global Optimization of PtCo Clusters

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