  We investigate the steady-state electronic transport through a suspended
dimer molecule coupled to leads. When strongly coupled to a vibrational mode,
the electron transport is enhanced at the phonon resonant frequency and
higher-order resonances. The temperature and bias determines the nature of the
phonon-assisted resonances, with clear absorption and emission peaks. The
strong coupling also induces a Frank-Condon-like blockade, suppressing the
current between the resonances. We compare an analytical polaron transformation
method to two exact numerical methods: the Hierarchy equations of motion and an
exact diagonalization in the Fock basis. In the steady--state, our two
numerical results are an exact match and qualitatively reflect the main
features of the polaron treatment. Our results indicate the possibility of a
new type of molecular transistor or sensor where the current can be extremely
sensitive to small changes in the energies of the electronic states in the
dimer.
