Nonequilibrium molecular dynamics studies of heat flow in one-dimensional systems

A nonequilibrium molecular dynamics (NEMD) heat flow algorithm is used to c ompute the heat conductivity of one-dimensional (ID) lattices. For the well -known Fermi-Pasta-Ulam (FPU) lattice, it is shown that for heat field stre ngths higher than a certain critical value, a stable solitary wave (soliton ) can emerge spontaneously in molecular dynamics simulations. For lower fie ld strengths the dynamics of the system are mostly chaotic. heat conductivi ty 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.