At the same time, energy is subtracted from two heat sinks (T l = T -20K, each 5 Å in size) placed at the edges of the box, as shown in Figure (a). The velocity rescaling method is used to maintain the desired temperatures at the heat source and sinks. A steady state with a stable temperature gradient is achieved after 10 ns NEMD. Subsequently, additional production runs are performed to calculate the thermal conductivity κ using the Fourier's law: