Structural Transitions and Melting in LJ74-78 Lennard-Jones Clusters from Adaptive Exchange Monte Carlo Simulations

Mandelshtam, Vladimir A.; Frantsuzov, Pavel A.; Calvo, F.

doi:10.1021/jp055839l

Cited by 54 publications

(72 citation statements)

References 37 publications

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“…42 Solid-solid structural transitions are frequently found to precede melting for Lennard-Jones ͑LJ͒ clusters, resulting in two well-resolved peaks in heat capacity. [44][45][46][47][48][49][50] For example, using exchange Monte Carlo simulations Mandelshtam et al found that LJ n clusters with n = 74-78 have two peaks in their heat capacities. 46 The peak at higher temperatures is attributed to a melting transition, and the lower temperature peak is assigned to a solid-to-solid structural transition from the decahedral ground state to an icosahedral geometry.…”

Section: Introductionmentioning

confidence: 99%

Metal clusters with hidden ground states: Melting and structural transitions in Al115+, Al116+, and Al117+

Cao

Starace

Judd

et al. 2009

The Journal of Chemical Physics

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Heat capacities measured as a function of temperature for Al(115)(+), Al(116)(+), and Al(117)(+) show two well-resolved peaks, at around 450 and 600 K. After being annealed to 523 K (a temperature between the two peaks) or to 773 K (well above both peaks), the high temperature peak remains unchanged but the low temperature peak disappears. After considering the possible explanations, the low temperature peak is attributed to a structural transition and the high temperature peak to the melting of the higher enthalpy structure generated by the structural transition. The annealing results show that the liquid clusters freeze exclusively into the higher enthalpy structure and that the lower enthalpy structure is not accessible from the higher enthalpy one on the timescale of the experiments. We suggest that the low enthalpy structure observed before annealing results from epitaxy, where the smaller clusters act as a nucleus and follow a growth pattern that provides access to the low enthalpy structure. The solid-to-solid transition that leads to the low temperature peak in the heat capacity does not occur under equilibrium but requires a superheated solid.

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Section: Introductionmentioning

confidence: 99%

Metal clusters with hidden ground states: Melting and structural transitions in Al115+, Al116+, and Al117+

Cao

Starace

Judd

et al. 2009

The Journal of Chemical Physics

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show abstract

“…In such transitions, the structure having the lowest energy also has the lowest entropy. Only in very few cases the direct simulation of temperature-induced structural transition has been possible, thanks to the use of parallel tempering Monte Carlo [47][48][49]. However, for oxygen clusters described with the EKB potential and containing about 100 molecules, even parallel tempering is probably not powerful enough to sample structural transitions.…”

Section: Solid-solid Transitionsmentioning

confidence: 99%

Onset of crystalline order in oxygen clusters

Calvo

Torchet

2007

Journal of Crystal Growth

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“…The vibrational properties of clusters and small particles have been studied very intensively [19][20][21][22][23][24][25][26], and are vital for understanding and describing the atomic interactions in the cluster [27][28][29][30][31][32]. Thermal properties like heat capacity and thermal conductivity as well as many other material properties are strongly influenced by the vibrational density of states (VDOS).…”

Section: Introductionmentioning

confidence: 99%

Effect of Size, Temperature, and Structure on the Vibrational Heat Capacity of Small Neutral Gold Clusters

Vishwanathan¹,

Springborg²

2017

J Material Sci Eng

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The vibrational heat capacity Cvib of a re-optimized neutral gold cluster was investigated at temperatures 0.5-300 K. The vibrational frequency of an optimized cluster was revealed by small atomic displacements using a numerical finite-differentiation method. This method was implemented using density-functional tight-binding (DFTB) approach. The desired set of system Eigen frequencies (3N -6) was obtained by diagonalization of the symmetric positive semi definite Hessian matrix. Our investigation revealed that the Cvib curve is strongly influenced by temperature, size, and structure and bond-order dependency. The effect of the range of interatomic forces is studied; especially the lower frequencies make a significant contribution to the heat capacity at low temperatures. In addition to that, we have exactly predicted the vibrational frequencies (ωi) which occur between 0.55 to 370.72 cm-1, depending on the nanoparticle morphology at T=0 for small neutral gold clusters AuN=3-20. This result has been proved and confirmed by the size effect values. It was found that beside the particle size, geometric shape, defect structure and an increase in asymmetry of nanoparticles effects on heat capacity. Surprisingly, the Boson peaks are typically ascribed to an excess density of vibrational states for the small clusters. Finally, temperature dependencies of the vibrational heat capacities of the re-optimized neutral gold clusters have been studied for the first time.

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Structural Transitions and Melting in LJ₇₄_-₇₈ Lennard-Jones Clusters from Adaptive Exchange Monte Carlo Simulations

Cited by 54 publications

References 37 publications

Metal clusters with hidden ground states: Melting and structural transitions in Al115+, Al116+, and Al117+

Metal clusters with hidden ground states: Melting and structural transitions in Al115+, Al116+, and Al117+

Onset of crystalline order in oxygen clusters

Effect of Size, Temperature, and Structure on the Vibrational Heat Capacity of Small Neutral Gold Clusters

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