NR Quintero, B Sánchez-Rey and J Casado-Pascual (pdf copy 37 Kb)

Abstract:

Very recently Willis et al. [Phys. Rev. E 69, 056612 (2004)] have used a collective variable theory to explain the appearance of a nonzero energy current in an ac driven, damped sine-Gordon equation. In this comment, we prove rigorously that the time-averaged energy current in an ac driven nonlinear Klein-Gordon system is strictly zero.