Finite-temperature behavior of small silicon and tin clusters: An<i>ab initio</i>molecular dynamics study

Krishnamurty, Saïlaja; Joshi, Kavita; Kanhere, D. G.; Blundell, S. A.

doi:10.1103/physrevb.73.045419

Cited by 41 publications

(63 citation statements)

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“…This may be an indication that small tin clusters adopt rather a covalent bonding nature than a metallic one, as already suggested by melting temperature measurements and calculations for small tin clusters. 5,6,[73][74][75][76][77] Sn 10s_0 stands out, exhibiting the smallest polarizability per atom within the range of clusters presented here. In comparison with the tetracapped trigonal prism structure of Sn 10s_0 , all following clusters, with the exception of Sn 17s_0 , can be regarded as somewhat elongated and clusters Sn 18s_0 -Sn 20s_0 as distinctively prolate.…”

Section: Resultsmentioning

confidence: 98%

Electronic properties for small tin clusters Sn_n (n ≤ 20) from density functional theory and the convergence toward the solid state

2009

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Global minimum structures of neutral tin clusters with up to 20 atoms obtained recently from genetic algorithm simulations within a density-functional approach (Schäfer et al., J Phys Chem A 2008, 112, 12312) were used to evaluate the corresponding electronic properties. The evolution of these properties with increasing cluster size is discussed in detail and compared with the lighter silicon and germanium clusters. We also discuss the extrapolation of these properties to the bulk limit.

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Section: Resultsmentioning

confidence: 98%

Electronic properties for small tin clusters Sn_n (n ≤ 20) from density functional theory and the convergence toward the solid state

2009

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“…Further, it is noted that this size sensitive nature in small clusters is related to the evolutionary pattern seen in their ground states and is seen to exist in clusters of sodium, gallium and aluminum. 24,34,35 In what follows, we show that this dramatic variation in the shape of heat capacity curve is also observed in the present pair of gold clusters viz., Au 19 and Au 20 . This observation has also thrown light on additional factors responsible for a continuous melting transition in clusters.…”

Section: Introductionmentioning

confidence: 99%

Ab Initio Molecular Dynamical Investigation of the Finite Temperature Behavior of the Tetrahedral Au₁₉ and Au₂₀ Clusters

Krishnamurty¹,

Shafai²,

Kanhere³

et al. 2007

J. Phys. Chem. A

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Density functional molecular dynamics simulations have been carried out to understand the finite temperature behavior of Au19 and Au20 clusters. Au20 has been reported to be a unique molecule having tetrahedral geometry, a large HOMO-LUMO energy gap and an atomic packing similar to that of the bulk gold (J. Li et al., Science, 299 864, 2003). Our results show that the geometry of Au19 is exactly identical to that of Au20 with one missing corner atom (called as vacancy). Surprisingly, our calculated heat capacities for this nearly identical pair of gold cluster exhibit dramatic differences. Au20 undergoes a clear and distinct solid like to liquid like transition with a sharp peak in the heat capacity curve around 770 K. On the other hand, Au19 has a broad and flat heat capacity curve with continuous melting transition. This continuous melting transition turns out to be a consequence of a process involving series of atomic rearrangements along the surface to fill in the missing corner atom. This results in a restricted diffusive motion of atoms along the surface of Au19 between 650 K to 900 K during which the shape of the ground state geometry is retained. In contrast, the tetrahedral structure of Au20 is destroyed around 800 K, and the cluster is clearly in a liquid like state above 1000 K. Thus, this work clearly demonstrates that (i) the gold clusters exhibit size sensitive variations in the heat capacity curves and (ii) the broad and continuous melting transition in a cluster, a feature which has so far been attributed to the disorder or absence of symmetry in the system, can also be a consequence of a defect (absence of a cap atom) in the structure.

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“…The explanation and understanding of various experimental observations have come from the first-principles density functional (DF) simulations [6][7][8][9][10]. For example, the higher than bulk melting temperature for Sn and Ga clusters is understood as being due to the difference in the nature of bonding between the cluster and the bulk [6,8,10].…”

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“Magic Melters” Have Geometrical Origin

2006

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Recent experimental reports bring out extreme size sensitivity in the heat capacities of gallium and aluminum clusters. In the present work we report results of our extensive ab initio molecular dynamical simulations on Ga30 and Ga31, the pair which has shown rather dramatic size sensitivity. We trace the origin of this size sensitive heat capacities to the relative order in their respective ground state geometries. Such an effect of nature of the ground state on the characteristics of heat capacity is also seen in case of small gallium and sodium clusters, indicating that the observed size sensitivity is a generic feature of small clusters.

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Finite-temperature behavior of small silicon and tin clusters: Anab initiomolecular dynamics study

Cited by 41 publications

References 50 publications

Electronic properties for small tin clusters Sn_n (n ≤ 20) from density functional theory and the convergence toward the solid state

Electronic properties for small tin clusters Sn_n (n ≤ 20) from density functional theory and the convergence toward the solid state

Ab Initio Molecular Dynamical Investigation of the Finite Temperature Behavior of the Tetrahedral Au₁₉ and Au₂₀ Clusters

“Magic Melters” Have Geometrical Origin

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Finite-temperature behavior of small silicon and tin clusters: Anab initiomolecular dynamics study

Cited by 41 publications

References 50 publications

Electronic properties for small tin clusters Snn (n ≤ 20) from density functional theory and the convergence toward the solid state

Electronic properties for small tin clusters Snn (n ≤ 20) from density functional theory and the convergence toward the solid state

Ab Initio Molecular Dynamical Investigation of the Finite Temperature Behavior of the Tetrahedral Au19 and Au20 Clusters

“Magic Melters” Have Geometrical Origin

Contact Info

Product

Resources

About

Electronic properties for small tin clusters Sn_n (n ≤ 20) from density functional theory and the convergence toward the solid state

Electronic properties for small tin clusters Sn_n (n ≤ 20) from density functional theory and the convergence toward the solid state

Ab Initio Molecular Dynamical Investigation of the Finite Temperature Behavior of the Tetrahedral Au₁₉ and Au₂₀ Clusters