Artículos de revistas
Anharmonic effects on thermodynamic properties of a graphene monolayer
Fecha
2014-09Registro en:
Europhysics Letters - EPL,Les Ulis : EDP Sciences,v. 107, n. 5, p. 56004-p1-56004-p6, Sept. 2014
0295-5075
10.1209/0295-5075/107/56004
Autor
Silva, A. L. C.
Cândido, Ladir
Rabelo, J. N. Teixeira
Hai, Guo Qiang
Peeters, F. M.
Institución
Resumen
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 h-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 -6.4 × '10 POT. -6''K POT. -1' and it becomes positive for T > Tα = 358K. We find that quantum effects are significant for T < 1000 K. 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.