  We examine, using mixed classical-quantum electron-ion dynamics, electron
transfer in a donor-acceptor-like molecular junction system based on
polyacetylene. We identify two qualitatively-different transfer regimes:
hopping and tunnelling. We discuss the criteria for achieving each one and for
minimizing inelastic scattering and decoherence arising from the coupling to
the ions, and we connect our main results to quantities derived from electron
dynamics involving simpler, three-state model systems. We identify the
requirements to have near-ballistic transfer.
