Array-induced collective transport in the Brownian motion of coupled nonlinear oscillator systems

Brownian motion of an array of harmonically coupled particles subject to a periodic substrate potential, and driven by an external bias, is investigated. In the linear response limit (small bias), coupling between particles may enhance the diffusion process, depending on the competition between the harmonic chain and the substrate potential. An analytical formula of the diffusion rate for the single-particle case is also obtained. In the nonlinear response regime, the moving kink may become phase locked to its radiated phonon waves; hence the mobility of the chain may decrease as one increases the external force.