  Interference effects strongly affect the transport characteristics of a
benzene single-electron transistor (SET) and for this reason we call it
interference SET (I-SET). We focus on the effects of degeneracies between
many-body states of the isolated benzene. We show that the particular current
blocking and selective conductance suppression occurring in the benzene I-SET
are due to interference effects between the orbitally degenerate states.
Further we study the impact of reduced symmetry due to anchor groups or
potential drop over the molecule. We identify in the quasi-degeneracy of the
involved molecular states the necessary condition for the robustness of the
results.
