Anharmonic effects on thermodynamic properties of a graphene monolayer

We extend the unsymmetrized self-consistent-field method (USF) for anharmonic crystals to layered non-Bravais crystals to investigate structural, dynamical and thermodynamic properties of a free-standing graphene monolayer. In this theory, the main anharmonicity of the crystal lattice has been inclu...

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Bibliographic Details
Published in:Europhysics letters 2014-09, Vol.107 (5), p.56004-p1-56004-p6
Main Authors: da Silva, A. L. C., Cândido, Ladir, Teixeira Rabelo, J. N., Hai, G.-Q., Peeters, F. M.
Format: Article
Language:English
Subjects:
65.40.De
65.80.Ck
68.65.Pq
Anharmonicity
Bravais crystals
Crystal lattices
Crystal structure
Density
Graphene
Interatomic distance
Lattice vibration
Monolayers
Nanostructure
Particle density (concentration)
Room temperature
Temperature dependence
Thermal expansion
Thermodynamic properties
Thermodynamics
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Summary:We extend the unsymmetrized self-consistent-field method (USF) for anharmonic crystals to layered non-Bravais crystals to investigate structural, dynamical and thermodynamic properties of a free-standing graphene monolayer. In this theory, the main anharmonicity of the crystal lattice has been included and the quantum corrections are taken into account in an -expansion for the one-particle density matrix. The obtained result for the thermal expansion coefficient (TEC) of graphene shows a strong temperature dependence and agrees with experimental results by Bao et al. (Nat. Nanotechnol., 4 (2009) 562). The obtained value of TEC at room temperature (300 K) is and it becomes positive for . We find that quantum effects are significant for . The interatomic distance, effective amplitudes of the graphene lattice vibrations, adiabatic and isothermal bulk moduli, isobaric and isochoric heat capacities are also calculated and their temperature dependences are determined.
ISSN:0295-5075
1286-4854
DOI:10.1209/0295-5075/107/56004