Three-dimensional global optimization of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msubsup><mml:mrow><mml:mi mathvariant="normal">Na</mml:mi></mml:mrow><mml:mrow><mml:mi>n</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msubsup></mml:mrow></mml:math>sodium clusters in the range<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>n</mml:mi><mml:mo>&lt;~</mml:mo><mml:mn>40</mml:mn></mml:math>

Calvo, F.; Tran, Suzanne; Blundell, S. A.; Guet, C.; Spiegelmann, F.

doi:10.1103/physrevb.62.10394

Cited by 23 publications

(13 citation statements)

References 84 publications

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“…The stable structures of Na 41 + predicted by the two potentials also have a polyicosahedral character, in agreement with the work of Ref. [22] on similar clusters. The caloric curves, also corrected for vibrational delocalization using the Pitzer-Gwinn approximation [23,24], are shown in figure 3 together with the present experimental measurements.…”

Section: Iv) Theoretical Caloric Curve Of Nasupporting

confidence: 90%

Two-step melting of Na41+

Zamith

Labastie

Chirot

et al. 2010

The Journal of Chemical Physics

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The heat capacity of the mass selected Na(41) (+) cluster has been measured using a differential nanocalorimetry method. A two-peak structure appears in the heat capacity curve of Na(41) (+), whereas Schmidt and co-workers [M. Schmidt, J. Donges, Th. Hippler, and H. Haberland, Phys. Rev. Lett. 90, 103401 (2003)] observed, within their experimental accuracy, a smooth caloric curve. They concluded from the absence of any structure that there is a second order melting transition in Na(41) (+) with no particular feature such as premelting. The observed difference with the latter results is attributed to the better accuracy of our method owing to its differential character. The two structures in the heat capacity are ascribed to melting and premelting of Na(41) (+). The peak at lower temperature is likely due to an anti-Mackay to Mackay solid-solid transition.

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Section: Iv) Theoretical Caloric Curve Of Nasupporting

confidence: 90%

Two-step melting of Na41+

Zamith

Labastie

Chirot

et al. 2010

The Journal of Chemical Physics

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“…Our finding of preferential polyicosahedral packing is in qualitative agreement with a basin hopping global optimization performed by Calvo et al 48 who found evidence for this particular atomic packing employing three different energy models for Na clusters. Preference for a polyicosahedral packing has also been observed in Lennard-Jones clusters in a similar size range.…”

Section: A Structuresupporting

confidence: 92%

Small sodium clusters that melt gradually: Melting mechanisms inNa30

Aguado¹,

López²

2006

Phys. Rev. B

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The meltinglike transition of Na 30 is studied by orbital-free density-functional molecular dynamics simulations. The potential energy surface of Na 30 is sampled by simulated annealing and regular quenchings performed along the dynamical trajectories. Both the ground-state structure and low-energy structural excitations are found to exhibit substantial polyicosahedral ordering. The most relevant feature of the potential energy landscape for the melting problem is the existence of many different structural isomers within an energy range of 1 meV/atom, resembling that of a glassy system ͑yet the structures have a high symmetry͒. The liquid phase is accessed gradually, with some isomerizations observed at a temperature as low as 30 K, while melting can be considered complete above approximately 200 K. The different dynamical mechanisms that allow the smooth opening of phase space available to the system as a function of temperature are identified and discussed. They can be classified in two different categories: ͑a͒ those that allow the exploration of isomers similar to the ground state, involving mainly surface isomerizations and surface melting, and leaving the structure of the cluster core unchanged; and ͑b͒ those associated with a more substantial structural change, more similar to the usual solid-solid phase transition in bulk phases; the structure of the cluster core changes only in this second type of transition. Mechanism ͑a͒ results in surface melting of the corresponding isomer upon heating; at that stage, mechanism ͑b͒ acts to transfer some excess energy from the surface to the core region, so that the surface melting is transiently avoided. Even in the fully developed liquid state, there are important differences from the bulk liquid due to the presence of the surface.

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“…3,[16][17][18] The configuration for Na 3 C 60 speculated by Roques et al 18 is found to be around 0.2 eV higher in total energy for the anionic Na 3 C 60 − cluster, confirming the charge effects on the structures of small size clusters. [24][25][26][27][28] From the size of 5, the sodium aggregation configuration can be decomposed into the geometrical units of trimer and tetrahedron. For example, the ground state (GS) structure of Na 6 C 60 − consists of two tetrahedrons which is calculated to be around 0.9 eV lower in energy than the one of two trimers with each Na adhered upon the pentagonal centers hypothesized in experimental studies.…”

Section: Resultsmentioning

confidence: 99%

Insight into the vertical detachment energy oscillation of NanC60− clusters

Wang

Xiu

et al. 2012

The Journal of Chemical Physics

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We have performed a detailed density functional theory study on the structural and electronic properties of Na(n)C(60)(-) (n = 1-12) clusters. The calculated vertical detachment energies show good agreement with the experimental data, which confirms the 3p (n = 3p) oscillation rule. The oscillation can be attributed to the combination of the charge depletion distribution induced by removing electrons and the number of the sodium atoms in direct contact with the fullerene. Based on the structural and electronic properties, the Na atoms can be categorized into two groups, one is for the metal atoms directly bonded to the fullerene surface, and the other one is for those without bonding to the fullerene. The Na atoms in group one would donate electrons to both the fullerene and the Na atoms in group two. As the total number of the sodium atoms increases, the number of Na atoms in group one would continue increasing till the size n = 3p - 1 to meet a shoulder from n = 3p - 1 to n = 3p, which accounts for the maximum vertical detachment energy at the size of n = 3p as drawn from the detailed electronic property studies.

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Three-dimensional global optimization ofNan+sodium clusters in the rangen<~40

Cited by 23 publications

References 84 publications

Two-step melting of Na41+

Two-step melting of Na41+

Small sodium clusters that melt gradually: Melting mechanisms inNa30

Insight into the vertical detachment energy oscillation of NanC60− clusters

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