A comparative study on phonon spectrum and thermal properties of graphene, silicene and phosphorene

On the basis of first-principle calculation using density functional theory, we systematically investigate the vibrational properties and thermal properties of two-dimensional honeycomb lattices: graphene, silicene and black phosphorene. We focus on the similarities and differences of their properties, and try to understand them from their lattice structures. We illustrate that, a phonon band gap develops in silicene and black phosphorene which reduce effectively the phonon thermal conductivity. All the systems (graphene, silicene and black phosphorene) have positive frequencies which ensure their structural stability. Also, we found that the specific heat, entropy and free energy for all the systems increases rapidly at very low temperature and specific heat (Cv) become constant at higher temperature.On the basis of first-principle calculation using density functional theory, we systematically investigate the vibrational properties and thermal properties of two-dimensional honeycomb lattices: graphene, silicene and black phosphorene. We focus on the similarities and differences of their properties, and try to understand them from their lattice structures. We illustrate that, a phonon band gap develops in silicene and black phosphorene which reduce effectively the phonon thermal conductivity. All the systems (graphene, silicene and black phosphorene) have positive frequencies which ensure their structural stability. Also, we found that the specific heat, entropy and free energy for all the systems increases rapidly at very low temperature and specific heat (Cv) become constant at higher temperature.