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Is the Antiresonance in Meta-Contacted Benzene Due to the Destructive Superposition of Waves Traveling Two Different Routes around the Benzene Ring?
journal contribution
posted on 2017-04-27, 00:00 authored by Daijiro Nozaki, Cormac ToherThe
well-known antiresonance around the middle of the HOMO–LUMO
gap observed in the transmission spectra of the meta-contacted benzene molecular junctions is often explained as being
caused by the destructive interference between electronic waves following
two different pathways in real space around the phenyl ring. We show
one contradictory scenario where this interpretation may break down
when one of the bonds in the benzene is attenuated gradually. Interestingly,
the dip in the transmission spectra is not attenuated at all even
after the complete breaking of the bond. This inconsistency arises
from the misinterpretation of the antiresonance observed in energy
space as a consequence of the superposition of waves propagating through
two independent pathways in real space. We revisit the Landauer model
within the Green’s function formalism and propose a different
interpretation of the appearance of the antiresonance in energy space
in meta-substituted benzene which is compatible with
the scenario described above. The quantum interference observed in
energy-dependent transmission spectra comes from cancellation between
the terms in the Green’s function and is effectively due to
interference between the different molecular orbitals.