Quantitative interpretation of the transition voltages in gold-poly(phenylene) thiol-gold molecular
junctions
Kunlin Wu1, Meilin Bai1, Stefano Sanvito2, Shimin Hou1, *
1 Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics,
Peking University, Beijing 100871, China
2 School of Physics and CRANN, Trinity College, Dublin 2, Ireland
1. Eigenchannel analysis of the gold-biphenyl thiol-gold junction in which the phenyl ring is
connected to the Au(111) surface directly
Figure S1 Charge density isosurfaces of the dominating eigenchannels of the gold–biphenyl thiol–gold
junction calculated at −1.66 eV (a), at -0.96 eV (b) and at 2.51 eV (c). Here, the phenyl ring is connected to
the Au(111) surface directly. The HOMO-1, HOMO and LUMO of the biphenyl thiol molecule in the gas
phase are also given for comparison.
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2. Transmission spectra of the gold-biphenyl thiol-gold junction in which the phenyl ring is
connected to the Au(111) surface directly
Figure S2 The equilibrium transmission spectra of the gold-biphenyl thiol-gold junctions at different goldphenyl distances: (a) 2.41 Å, (b) 3.08 Å, (c) 4.01 Å and (d) 4.98 Å. Here, the phenyl ring is connected to
the Au(111) surface directly.
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3. The geometrical structure and the transport properties of the gold-biphenyl thiol-gold junction
in which the phenyl ring is bonded to the Au(111) surface through a gold cluster with four atoms
arranged in a pyramid configuration
Figure S3 The optimized atomic structure (a), the equilibrium transmission spectrum (b) and the F-N plot (c)
of the gold-biphenyl thiol-gold junction, in which the phenyl ring is bonded to the Au(111) surface through
a gold cluster with four atoms arranged in a pyramid configuration. The inset of (c) is the I-V curve on a
linear scale.
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4. The geometrical structure and the transport properties of the gold-biphenyl thiol-gold junction
with the sulfur atom binding at the adatom site of the Au(111) surface
Figure S4 The optimized atomic structure (a), the equilibrium transmission spectrum (b), the I-V curve on a
linear scale (c) and the F-N plot (d) of the gold-biphenyl thiol-gold junction, in which the sulfur atom binds
at the adatom site of the Au(111) surface.
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5. The geometrical structure and the transport properties of the gold-terphenyl thiol-gold
junctions
Figure S5: Optimized atomic structure (a), zero-bias transmission spectrum (b) and the F-N plot (c) of the
gold-terphenyl thiol-gold junction in which the phenyl ring is bonded to the Au(111) surface through a gold
adatom. For the gold-terphenyl thiol-gold junction with the phenyl ring bonded to the Au(111) surface
through a four-atom gold cluster in a pyramid configuration, the same quantities are plotted in panels (d) to
(f). In the inserts of panels (c) and (f), the I-V curves are shown on standard axes.
Table S1 The transition voltages and the transmission coefficients at the Fermi level of the
Au/terphenyl thiol/Au junctions with different Au-H distances, in which the phenyl ring is
connected to the Au(111) surface directly.
Distance (Å)
Vtrans (V)
T(EF)
2.11
0.6
8.5×10-4
2.95
0.6
1.1×10-4
3.97
0.6
8.1×10-6
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6. The geometrical structure and the transport properties of the gold-benzene thiol-gold junctions
Figure S6: Optimized atomic structure (a), zero-bias transmission spectrum (b) and the F-N plot (c) of the
gold-benzene thiol-gold junction in which the phenyl ring is bonded to the Au(111) surface through a gold
adatom. For the gold-benzene thiol-gold junction with the phenyl ring bonded to the Au(111) surface
through a four-atom gold cluster in a pyramid configuration, the same quantities are plotted in panels (d) to
(f). In the inserts of panels (c) and (f), the I-V curves are shown on standard axes.
Table S2 The transition voltages and the transmission coefficients at the Fermi level of the
Au/benzene thiol/Au junctions with different Au-H distances, in which the phenyl ring is
connected to the Au(111) surface directly.
Distance (Å)
Vtrans (V)
T(EF)
3.13
0.9
1.3×10-3
4.14
0.8
9.7×10-5
5.15
0.9
4.1×10-6
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7. The transport properties of the gold-benzene thiol-gold junction calculated using the LDA
functional, in which the phenyl ring is bonded to the Au(111) surface directly
Figure S7 Optimized atomic structure (a), zero-bias transmission spectrum (b) and the F-N plot (c) of the
gold-benzene thiol-gold junction calculated using the PZ LDA functional, in which the phenyl ring is
bonded to the Au(111) surface directly. The transition voltage is determined to be 0.83 V.
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