Nanoscale thermal conduction is a research hotspot in disciplines such as physics, materials science, and engineering thermophysics. In emerging low-dimensional nanomaterials, many novel and even anomalous thermal conduction phenomena have been observed. For example, carbon nanotubes and graphene exhibit a transition from ballistic to diffusive transport, and their thermal conductivity is no longer a constant independent of sample length. Graphene shows ultrahigh thermal conductivity due to the selection rule of phonon scattering. Monolayer molybdenum disulfide exhibits ultralow thermal conductivity, and phosphorene exhibits thermal anisotropy. In two-dimensional boron, there are one-dimensional ultra-high phonon thermal conductivity phenomena, and so on.
To investigate thermal conduction in solid materials, researchers have developed various methods, including molecular dynamics, non-equilibrium Green's function method, phonon Boltzmann transport equation, and transmission matrix, among others. These computational methods can efficiently calculate the thermal transport behavior of low-dimensional materials, discover unique physical mechanisms in these materials, and provide prior guidance for experimental research.
