  We study one-dimensional systems with random diagonal disorder but
off-diagonal short-range correlations imposed by structural constraints. We
find that these correlations generate effective conduction channels for finite
systems. At a certain golden correlation condition for the hopping amplitudes,
we find an extended state for an infinite system. Our model has important
implications to charge transport in DNA molecules, and a possible set of
experiments in semiconductor superlattices is proposed to verify our most
interesting theoretical predictions.
