Anharmonic on-site potential implies asymmetry thermal transport in 1D mass-graded harmonic lattice

Exploring the thermal rectification in one-dimensional (1D) lattice model is of considerable practical importance. Here we consider the 1D mass-graded harmonic lattice with on-site potential. By the nonequilibrium molecular dynamics simulation, it is uncovered that the temperature gradient is formed regardless of the fact that the on-site potential is harmonic or anharmonic. Differently, the thermal rectification rises in the model with anharmonic on-site potential whereas disappears with harmonic one. Moreover, we find that the heat flux of 1D mass-graded Frenkel–Kontorova (FK) model in the direction of mass increasing is larger than that in the direction of mass decreasing. Our results further emphasize that nonlinearity is necessary for thermal rectification.