Elastic and non-linear stiffness of graphene: a simple approach

The recent experiment [Science \textbf{321}, 385 (2008)] on the Young's modulus and third-order elastic stiffness of graphene are well explained in a very simple approach, where the graphene is described by a simplified system and the force constant for the non-linear interaction is estimated from the Tersoff-Brenner potential.Comment: 4 pages, 4 figure

How Does Folding Modulate Thermal Conductivity of Graphene

We study thermal transport in folded graphene nanoribbons using molecular dynamics simulations and the non-equilibrium Green's function method. It is found that the thermal conductivity of flat graphene nanoribbons can be modulated by folding and changing interlayer couplings. The analysis of transmission reveals that the reduction of thermal conductivity is due to scattering of low frequency phonons by the folds. Our results suggest that folding can be utilized in the modulation of thermal transport properties in graphene and other two dimensional materials.Comment: published in Applied Physics Letters 201

Edge states induce boundary temperature jump in molecular dynamics simulation of heat conduction

We point out that the origin of the commonly occurred boundary temperature jump in the application of No\'se-Hoover heat bath in molecular dynamics is related to the edge modes, which are exponentially localized at the edge of the system. If heat baths are applied to these edge regions, the injected thermal energy will be localized thus leading to a boundary temperature jump. The jump can be eliminated by shifting the location of heat baths away from edge regions. Following this suggestion, a very good temperature profile is obtained without increasing any simulation time, and the accuracy of thermal conductivity calculated can be largely improved.Comment: accepted by PRB, brief report, references added, typo correcte

Isotopic effects on the thermal conductivity of graphene nanoribbons: localization mechanism

Thermal conductivity of graphene nanoribbons (GNR) with length 106~{\AA} and width 4.92~{\AA} after isotopic doping is investigated by molecular dynamics with quantum correction. Two interesting phenomena are found: (1) isotopic doping reduces thermal conductivity effectively in low doping region, and the reduction slows down in high doping region; (2) thermal conductivity increases with increasing temperature in both pure and doped GNR; but the increasing behavior is much more slowly in the doped GNR than that in pure ones. Further studies reveal that the physics of these two phenomena is related to the localized phonon modes, whose number increases quickly (slowly) with increasing isotopic doping in low (high) isotopic doping region.Comment: 6 fig