Modeling the Phase Diagram of Carbon

Ghiringhelli, Luca M.; Los, J.; Meijer, Evert Jan; Fasolino, A.; Frenkel, Daan

doi:10.1103/physrevlett.94.145701

Cited by 136 publications

(119 citation statements)

References 27 publications

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“…5,31,[53][54][55] In particular, it was used to predict the carbon phase diagram comprising graphite, diamond, and the liquid, showing its accuracy by comparison of the predicted graphite-diamond line with experimental data. 56 In the case of graphene, this effective potential has been found to give a good description of elastic properties such as the Young's modulus. 53,57 Also, the interatomic potential employed here yields at 300 K a bending modulus κ = 1.6 eV for graphene at 300 K. 32 This value is close to the best fit to experimental and theoretical results obtained for κ by Lambin.…”

Section: Methodsmentioning

confidence: 99%

Quantum effects in graphene monolayers: Path-integral simulations

Herrero

Ramı́rez

2016

The Journal of Chemical Physics

113

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Path-integral molecular dynamics (PIMD) simulations have been carried out to study the influence of quantum dynamics of carbon atoms on the properties of a single graphene layer. Finitetemperature properties were analyzed in the range from 12 to 2000 K, by using the LCBOPII effective potential. To assess the magnitude of quantum effects in structural and thermodynamic properties of graphene, classical molecular dynamics simulations have been also performed. Particular emphasis has been laid on the atomic vibrations along the out-of-plane direction. Even though quantum effects are present in these vibrational modes, we show that at any finite temperature classical-like motion dominates over quantum delocalization, provided that the system size is large enough. Vibrational modes display an appreciable anharmonicity, as derived from a comparison between kinetic and potential energy of the carbon atoms. Nuclear quantum effects are found to be appreciable in the interatomic distance and layer area at finite temperatures. The thermal expansion coefficient resulting from PIMD simulations vanishes in the zero-temperature limit, in agreement with the third law of thermodynamics.

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Section: Methodsmentioning

confidence: 99%

Quantum effects in graphene monolayers: Path-integral simulations

Herrero

Ramı́rez

2016

The Journal of Chemical Physics

113

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“…The energy of a given configuration is evaluated according to the bond order potential LCBOPII developed in the recent past [12]. This potential is based on a large database of experimental and theoretical data for molecules and solids and has been proven to describe very well thermodynamic and structural properties of all phases of carbon and its phase diagram in a wide range of temperatures and pressures [12,14].…”

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confidence: 99%

Intrinsic ripples in graphene

2007

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The stability of two-dimensional (2D) layers and membranes is subject of a long standing theoretical debate. According to the so called Mermin-Wagner theorem, long wavelength fluctuations destroy the long-range order for 2D crystals. Similarly, 2D membranes embedded in a 3D space have a tendency to be crumpled. These dangerous fluctuations can, however, be suppressed by anharmonic coupling between bending and stretching modes making that a two-dimensional membrane can exist but should present strong height fluctuations. The discovery of graphene, the first truly 2D crystal and the recent experimental observation of ripples in freely hanging graphene makes these issues especially important. Beside the academic interest, understanding the mechanisms of stability of graphene is crucial for understanding electronic transport in this material that is attracting so much interest for its unusual Dirac spectrum and electronic properties. Here we address the nature of these height fluctuations by means of straightforward atomistic Monte Carlo simulations based on a very accurate many-body interatomic potential for carbon. We find that ripples spontaneously appear due to thermal fluctuations with a size distribution peaked around 70 \AA which is compatible with experimental findings (50-100 \AA) but not with the current understanding of stability of flexible membranes. This unexpected result seems to be due to the multiplicity of chemical bonding in carbon.Comment: 14 pages, 6 figure

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“…For instance, experimentally shock-compressed graphite can span porosity rates ranging up to more than 20%, yielding graphite to diamond (G/D) transition pressures from 18 to 45 GPa. These values lie substantially above the estimated G/D coexistence line (in the 5-8 GPa range according to experiments and simulations [2,10,11]), which signs a possible metastability of shocked graphite in the diamondpredominant regime (reversely, diamond is well-known to be metastable in the low temperature/pressure regime, where graphite is the most stable phase). This effect results in a wide spread of experimental data in the G/D transition regime [12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 93%

Theoretical study of the porosity effects on the shock response of graphitic materials

Pineau

Bourasseau

Maillet

et al. 2015

EPJ Web of Conferences

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Abstract. In this paper we present a theoretical study of the shock compression of porous graphite by means of combined Monte Carlo and molecular dynamics simulations using the LCBOPII potential. The results show that the Hugoniostat methods can be used with "pole" properties calculated from porous models to reproduce the experimental Hugoniot of pure graphite and diamond with good accuracy. The computed shock temperatures show a sharp increase for weak shocks which we analyze as the heating associated with the closure of the initial porosity. After this initial phase, the temperature increases with shock intensity at a rate comparable to monocrystalline graphite and diamond. These simulations data can be exploited in view to build a full equation of state for use in hydrodynamic simulations.

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Modeling the Phase Diagram of Carbon

Cited by 136 publications

References 27 publications

Quantum effects in graphene monolayers: Path-integral simulations

Quantum effects in graphene monolayers: Path-integral simulations

Intrinsic ripples in graphene

Theoretical study of the porosity effects on the shock response of graphitic materials

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