Modeling Germanene Monolayer: Interaction Potentials and Insights into the Phonon Thermal Conductivity

Due to the unique and intriguing buckled topology, modeling and understanding thermal transport is challenging in germanene 2D materials. We examine the suitability of Tersoff and Stillinger–Weber interaction potentials to model the germanene monolayer and investigate the phonon thermal conductivity. We find that the widely used Tersoff interaction potential cannot accurately reproduce the experimental structure of the germanene monolayer at higher temperatures. However, we observed that Stillinger–Weber potential with optimized parameters satisfactorily reproduces the structure and buckling of germanene monolayer over a wide range of temperatures and is quite suitable for studying thermal conductivity of germanene. We used molecular dynamics simulations to generate 30 independent equilibrium trajectories at a given temperature to understand the thermal conductivity in the germanene monolayer. Our simulations predict that the thermal conductivity of the germanene monolayer is 3.6 \(\pm\) 0.4 W/(m.K) at room temperature, which further decreases rapidly with temperature. The thermal conductivity of germanene is found to be much lower than that of graphene and silicene at any temperature.