Structural distortions in metal clusters

Yi, Jae‐Yel; Oh, Deuk-Ja; Bernholc, J.

doi:10.1103/physrevlett.67.1594

Cited by 104 publications

(65 citation statements)

References 22 publications

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“…In the case of Al 2 , the triplet state was found to be more stable than the singlet state by 7.76 kcal/mol, while for Al 6 more stable than the singlet state by 3.5 kcal/mol. For Al 11 , it was found that the spin doublet state was more stable than the spin quartet state by 9.17 kcal/mol.…”

Section: A Heats Of Formation and Geometry Of Clustersmentioning

confidence: 99%

“…5 Other theoretical computations [6][7][8][9][10][11] have tackled issues to do with the energetically lowest structures of small aluminum clusters, although even for small clusters such as Al 4 , Al 5 , and Al 7 there are still lingering uncertainties on the preferred configurations. The other point of interest is the existence of magic clusters ͑superatoms͒ of aluminum.…”

Section: Introductionmentioning

confidence: 99%

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Predictions of melting, crystallization, and local atomic arrangements of aluminum clusters using a reactive force field

Ojwang

Santen

Kramer

et al. 2008

The Journal of Chemical Physics

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A parametrized reactive force field model for aluminum ReaxFF Al has been developed based on density functional theory ͑DFT͒ data. A comparison has been made between DFT and ReaxFF Al outputs to ascertain whether ReaxFF Al is properly parametrized and to check if the output of the latter has correlation with DFT results. Further checks include comparing the equations of state of condensed phases of Al as calculated from DFT and ReaxFF Al . There is a good match between the two results, again showing that ReaxFF Al is correctly parametrized as per the DFT input. Simulated annealing has been performed on aluminum clusters Al n using ReaxFF Al to find the stable isomers of the clusters. A plot of stability function versus cluster size shows the existence of highly stable clusters ͑magic clusters͒. Quantum mechanically these magic clusters arise due to the complete filling of the orbital shells. However, since force fields do not care about electrons but work on the assumption of validity of Born-Oppenheimer approximation, the magic clusters are therefore correlated with high structural symmetry. There is a rapid decline in surface energy contribution due to the triangulated nature of the surface atoms leading to higher coordination number. The bulk binding energy is computed to be 76.8 kcal/mol. This gives confidence in the suitability of ReaxFF for studying and understanding the underlying dynamics in aluminum clusters. In the quantification of the growth of cluster it is seen that as the size of the clusters increase there is preference for the coexistence of fcc/hcp orders at the expense of simple icosahedral ordering, although there is some contribution from distorted icosahedral ordering. It is found that even for aluminum clusters with 512 atoms distorted icosahedral ordering exists. For clusters with N Ն 256 atoms fcc ordering dominates, which implies that at this point we are already on the threshold of bulklike bonding.

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Section: A Heats Of Formation and Geometry Of Clustersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Predictions of melting, crystallization, and local atomic arrangements of aluminum clusters using a reactive force field

Ojwang

Santen

Kramer

et al. 2008

The Journal of Chemical Physics

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“…These studies range from the simple jellium model [20] where the cluster geometry is ignored, to a number of models where the geometry explicitly enters into the picture including semiempirical molecular orbital calculations [21], quantum molecular dynamics [26,27,28,29,31], quantum-mechanical calculations based on quantumchemical [22,23,24] and density-functional [25,26,27,28,29,30,31,32,33] theories (DFT) within local density or local spin-density approximations, molecular dynamics and Monte Carlo simulations based on empirical model potentials [34,35,36,37,38,39]. Especially the icosahedral Al 13 has been studied intensively [24,32].…”

Section: A Aluminium Clustersmentioning

confidence: 99%

Global minima of Al_N, Au_Nand Pt_N,N⩽ 80, clusters described by the Voter–Chen version of embedded-atom potentials

Sebetci

Güvenç

2005

Modelling Simul. Mater. Sci. Eng.

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Using the basin-hopping Monte Carlo minimization approach we report the global minima for aluminium, gold and platinum metal clusters modelled by the Voter-Chen version of the embeddedatom model potential containing up to 80 atoms. The virtue of the Voter-Chen potentials is that they are derived by fitting to experimental data of both diatomic molecules and bulk metals simultaneously. Therefore, it may be more appropriate for a wide range of the size of the clusters. This is important since almost all properties of the small clusters are size dependent. The results show that the global minima of the Al, Au and Pt clusters have structures based on either octahedral, decahedral, icosahedral or a mixture of decahedral and icosahedral packing. The 54-atom icosahedron without a central atom is found to be more stable than the 55-atom complete icosahedron for all of the elements considered in this work. The most of the Al global minima are identified as some fcc structures and many of the Au global minima are found to be some low symmetric structures, which are both in agreement with the previous experimental studies.

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“…An interesting aspect of annealing studies which can be afforded on today's supercomputers is that each QMD run results in a significantly different structure. 14 An analysis based on the structure factors and distribution functions shows 14 that the local topology of each structure is almost the same, i.e., the nearest neighbor and the most probable angle peaks occur at exactly the same positions for the three annealed clusters, and there are strong similarities in the positions of second neighbor peaks. It follows that the energetics of A155 is mainly determined by the first and possibly second nearest neighbors.…”

mentioning

confidence: 99%

Clusters and cluster-assembled materials

1991

Materials & Design

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92-132059 2 95 18 wo33;: Review of Work To DateOur work falls naturally into three categories: i) local density calculations of cluster structures and the development of classical potentials, (ii) simulations of thermodynamic properties of clusters and their fusion, and (iii) macroscopic (continuum theory) modeling of the sintering process. These topics will be addressed in turn. Although the nominal focus of the proposal is on sintering processes, many issues important to sintering are generic in nature and thus also important in other areas of cluster science. These issues have been approached from a broad perspective, leading to results which impact the whole field of clusters and cluster-assembled materials. We have concentrated on Al, which is a "typical" free electron metal, and Cu, as a representative transition metal atom. For Al, we have carried out extensive Car-Parrineflo and DVM calculations for clusters containing up to 55 atoms. Larger clusters, containing up to 2000 atoms, were studied quantum-mechanically using a jellium model. For Cu, DVM calculations for clusters containing up to 13 atoms have served as a basis for improving existing, efficient but very approximate "embedded atom method" (EAM) potentials. The results of the calculations 2

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Structural distortions in metal clusters

Cited by 104 publications

References 22 publications

Predictions of melting, crystallization, and local atomic arrangements of aluminum clusters using a reactive force field

Predictions of melting, crystallization, and local atomic arrangements of aluminum clusters using a reactive force field

Global minima of Al_N, Au_Nand Pt_N,N⩽ 80, clusters described by the Voter–Chen version of embedded-atom potentials

Clusters and cluster-assembled materials

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Structural distortions in metal clusters

Cited by 104 publications

References 22 publications

Predictions of melting, crystallization, and local atomic arrangements of aluminum clusters using a reactive force field

Predictions of melting, crystallization, and local atomic arrangements of aluminum clusters using a reactive force field

Global minima of AlN, AuNand PtN,N⩽ 80, clusters described by the Voter–Chen version of embedded-atom potentials

Clusters and cluster-assembled materials

Contact Info

Product

Resources

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Global minima of Al_N, Au_Nand Pt_N,N⩽ 80, clusters described by the Voter–Chen version of embedded-atom potentials