Nonequilibrium Molecular Dynamics Studies of Heat Flow in One-Dimensional Systems

A nonequilibrium molecular dynamics (NEMD) heat flow algorithm is used to compute the heat conductivity of one-dimensional (1D) lattices. For the well-known Fermi Pasta Ulam (FPU) lattice, it is shown that for heat field strengths higher than a certain critical value, a stable solitary wave (soliton) can emerge spontaneously in molecular dynamics simulations. For lower field strengths the dynamics of the system are mostly chaotic; heat conductivity obtained via the NEMD algorithm increases monotonically with the size of the system. It is also demonstrated that the 1D nonequilibrium system may reach different steady states depending on the initial conditions.