Fig. 1. Non-equilibrium molecular dynamics simulation setup for the lamellar amorphous polyethylene (LAPE) chains. The size of the simulation box is around L = 20 nm and W = 4 nm. An individual polyethylene chain is highlighted in yellow. The high temperature thermostat (one red region with thickness of 10 Å) is applied to the center of the simulation domain, while the low temperature thermostat (two blue regions with thickness of 5 Å) is applied to the two ends. Periodic boundary conditions are used in all directions. This setup has a mirror symmetry that results in the bidirectional heat flow.