Abstract
We consider a model for stationary electronic transport through a one-dimensional chain of two leads attached to a perturbed central region (quantum dot) in the regime where the theory proposed recently by Čápek for a similar model of phonon transport predicts the striking phenomenon of a permanent current between the leads. We show that Čápek's results based on a rigorous but asymptotic Davies theory differ from direct transport calculations that yield, in full agreement with the second law of thermodynamics, zero current. We find the permanent current to be within the error of the asymptotic expansion for finite couplings, and identify cancelling terms of the same order.