Solid-liquid coexistence in small systems: A statistical method to calculate melting temperatures

Hong, Qi‐Jun; Walle, Axel van de

doi:10.1063/1.4819792

Cited by 55 publications

(51 citation statements)

References 47 publications

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“…have developed a new statistical method to quickly predict the melting points of materials. 12 They have made several remarkable predictions of new high temperature alloys using density functional theory to test the co-existence of solid and liquid phases. They recently identified a novel HfN 0.38 C 0.51 alloy with a remarkable predicted 4398 K melting point.…”

Section: Introductionmentioning

confidence: 99%

The initial stages of melting of graphene between 4000 K and 6000 K

Ganz

Yang

et al. 2017

Phys. Chem. Chem. Phys.

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Graphene and its analogues have some of the highest predicted melting points of any materials. Previous work estimated the melting temperature for freestanding graphene to be a remarkable 4510 K. However, this work relied on theoretical methods that do not accurately account for the role of bond breaking or complex bonding configurations in the melting process. Furthermore, experiments to verify these high melting points have been challenging. Practical applications of graphene and carbon nanotubes at high temperatures will require a detailed understanding of the behavior of these materials under these conditions. Therefore, we have used exclusively reliable ab initio molecular dynamics calculations to study the initial stages of melting of freestanding graphene monolayers between 4000 and 6000 K. To accommodate large defects, and for improved accuracy, we used a large 10 x 10 periodic unit cell. We find that the system can be heated up to 4500 K for 18 ps without melting, and 3-rings and short lived broken bonds (10-rings) are observed. At 4500 K, the system appears to be in a quasi-2D liquid state. At 5000 K, the system is starting to melt. During the 20 ps simulation, diffusion events are observed, leading to the creation of a 5775 defect. We calculate accurate excitation energies for these configurations, and the pair correlation function is presented. The modified Lindemann criterion was calculated. Graphene and nanotubes together with other proposed high melting point materials would be interesting candidates for experimental tests of melting in the weightless environment of space.

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Section: Introductionmentioning

confidence: 99%

The initial stages of melting of graphene between 4000 K and 6000 K

Ganz

Yang

et al. 2017

Phys. Chem. Chem. Phys.

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“…Our investigation focuses on the rocksalt structure in the Hf-Ta-C systems, because it is the only stable solidstate form in the temperature region of melting [26,27]. Employing the small-cell coexistence method [24], we calculate the melting temperatures of rocksalt HfC x (x ∈ [0.75, 1]), as shown in Fig. 1.…”

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confidence: 99%

“…We recently developed the small-size coexistence method [24,25], and managed to reduce the computer cost drastically. An automated computer code is prepared and freely distributed for direct DFT melting point calculations [25].…”

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confidence: 99%

Prediction of the material with highest known melting point fromab initiomolecular dynamics calculations

2015

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“…The accuracy (typically with an error smaller than 100K), robustness and efficiency of the method have been demonstrated in a range of materials [28][29][30][31][32][33][34] . Our investigation starts with sodium, an alkali element well known for re-entrant melting.…”

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Reentrant melting of sodium, magnesium, and aluminum: General trend

Hong

2019

Phys. Rev. B

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Re-entrant melting (in which a substance's melting point starts to decrease beyond a certain pressure) is believed to be an unusual phenomenon. Among the elements, it has so far only been observed in a very limited number of species, e.g., the alkali metals. Our density functional theory calculations reveal that this behavior actually extends beyond alkali metals to include magnesium, which also undergoes re-entrant melting, though at the much higher pressure of ∼300 GPa. We find that the origin of re-entrant melting is the faster softening of interatomic interactions in the liquid phase than in the solid, as pressure rises. We propose a simple approach to estimate pressure-volume relations and show that this characteristic softening pattern is widely observed in metallic elements. We verify this prediction in the case of aluminum by finding re-entrant melting at ∼4000 GPa. These results suggest that re-entrant melting may be a more universal feature than previously thought. * Re-entrant melting is generally considered an unusual phenomenon 1,2 that is associated with a negative slope of the melting temperature versus pressure line, or the melting curve.An "ordinary" melting curve, rising from low temperatures and pressures, may eventually invert its trend at some maximum temperature, with a change of slope from positive to negative values for increasing pressures. The resulting topology of the melting curve gives rise to re-entrant melting: upon compressing the liquid at temperatures lower than the maximum melting temperature, one observes a liquid-solid-liquid sequence of phases. In other words, the liquid phase, which is stable at low pressures, re-enters at higher pressures.

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Solid-liquid coexistence in small systems: A statistical method to calculate melting temperatures

Cited by 55 publications

References 47 publications

The initial stages of melting of graphene between 4000 K and 6000 K

The initial stages of melting of graphene between 4000 K and 6000 K

Prediction of the material with highest known melting point fromab initiomolecular dynamics calculations

Reentrant melting of sodium, magnesium, and aluminum: General trend

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