  Understanding the process of electron tunneling in chirality-induced
single-molecule junctions is imperative for the development of nanoscale
switching and artificial nanomotors. Based on the combined non-equilibrium
Green functions formalism and the ground-state density functional theory, we
present here the charge transport behavior of chiral gold (7,3) nanowires (NWs)
in comparison with various other chiral and achiral 1D gold nanostructures as
the principal leads to form stable single-molecule junctions. For
sigma-saturated alkane chains, we find that the contact potential barriers vary
widely with the achiral leads but not with the chiral ones, although a close
resemblance exists in the tunneling constants. Lower energy gaps for
single-molecule junctions with Au(7,3)NWs ensure better electronic conductance
even after allowing for the low thermal loss, due mainly to the close-packed
arrangements of atoms with minimum wire tension. Our first-principles quantum
transport analysis further suggests that chiral Au(7,3)NWs render higher
electronic conductance than chiral gold (5,3) nanotubes (NTs), once bridged by
either sigma-saturated or pi-conjugated molecular moieties. It, however, turns
out that asymmetricity in the characteristics of channel formation at the
lead-molecule contact remains often associated with chiral Au(7,3)NWs only.
