Understanding quantum interference in coherent molecular conduction

Solomon, Gemma C.; Andrews, David Q.; Hansen, Thorsten; Goldsmith, Randall H.; Wasielewski, Michael R.; Duyne, Richard P. Van; Ratner, Mark A.

doi:10.1063/1.2958275

Cited by 256 publications

(312 citation statements)

References 38 publications

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“…It has been reported that destructive QI exists in benzene with the meta connectivity and is responsible for the observed reduction of conductance 16,20,28 , whereas for para and ortho connectivities, constructive QI should be observed 44,45 . The transmission coefficient calculations through junctions where the metal-ring connection is artificially blocked (Fig.…”

Section: Discussionmentioning

confidence: 99%

A quantum circuit rule for interference effects in single-molecule electrical junctions

et al. 2015

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A quantum circuit rule for combining quantum interference effects in the conductive properties of oligo(phenyleneethynylene) (OPE)-type molecules possessing three aromatic rings was investigated both experimentally and theoretically. Molecules were of the type X-Y-X, where X represents pyridyl anchors with para (p), meta (m) or ortho (o) connectivities and Y represents a phenyl ring with p and m connectivities. The conductances G XmX (G XpX ) of molecules of the form X-m-X (X-p-X), with meta (para) connections in the central ring, were predominantly lower (higher), irrespective of the meta, para or ortho nature of the anchor groups X, demonstrating that conductance is dominated by the nature of quantum interference in the central ring Y. The single-molecule conductances were found to satisfy the quantum circuit rule G ppp /G pmp ¼ G mpm /G mmm . This demonstrates that the contribution to the conductance from the central ring is independent of the para versus meta nature of the anchor groups. S tudies of the electrical conductance of single molecules attached to metallic electrodes not only probe the fundamentals of quantum transport but also provide the knowledge needed to develop future molecular-scale devices and functioning circuits [1][2][3][4][5][6][7][8][9] . Owing to their small size (on the scale of Angstroms) and the large energy gaps (on the scale of eV), transport through single molecules can remain phase coherent even at room temperature, and constructive or destructive quantum interference (QI) can be utilized to manipulate their room temperature electrical 10-13 and thermoelectrical 14,15 properties. In previous studies, it was reported theoretically and experimentally that the conductance of a phenyl ring with meta (m) connectivity is lower than the isomer with para (p) connectivity by several orders of magnitude [16][17][18][19][20][21][22][23][24][25] . This arises because partial de Broglie waves traversing different paths through the ring are perfectly out of phase leading to destructive QI in the case of meta coupling, while for para or ortho coupling they are perfectly in phase and exhibit constructive QI. (See, for example, equation 8 of ref. 26.) It is therefore natural to investigate how QI in molecules with multiple aromatic rings can be utilized in the design of more complicated networks of interference-controlled molecular units.The basic unit for studying QI in single molecules is the phenyl ring, with thiol 17,21 , methyl thioether 27 , amine 17 or cyanide 19 anchors directly connecting the aromatic ring to gold electrodes. Recently, Arroyo et al. 28,29 studied the effect of QI in a central phenyl ring by varying the coupling to various anchor groups, including two variants of thienyl anchors. However, the relative importance of QI in central rings compared with QI in anchor groups has not been studied systematically because the thienyl anchors of Arroyo et al. 28,29 were five-membered rings, which exhibit only constructive interference. To study the relative effect of QI in anchors,...

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Section: Discussionmentioning

confidence: 99%

A quantum circuit rule for interference effects in single-molecule electrical junctions

et al. 2015

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“…Additionally, the lack of hybridization of the orbitals with the electrodes greatly simplifies the analysis of the features in the transmission. 18 This is especially important for molecules, which are expected to exhibit interference effects.…”

Section: Discussionmentioning

confidence: 99%

“…Examples include systems where quantum interference plays a role. [17][18][19][20] This necessitates accurate quantum chemical modeling of the molecule, while the details of the electrodes may be less important to transport. Several approximations exist that trade sophistication for efficiency in the description of the electrodes, [21][22][23][24][25] but to the best of our knowledge, there have been no systematic studies of the quality of the results obtained with such approximations.…”

Section: Introductionmentioning

confidence: 99%

Applicability of the wide-band limit in DFT-based molecular transport calculations

Verzijl¹,

Seldenthuis²,

Thijssen³

2013

The Journal of Chemical Physics

131

129

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Transport properties of molecular junctions are notoriously expensive to calculate with ab initio methods, primarily due to the semi-infinite electrodes. This has led to the introduction of different approximation schemes for the electrodes. For the most popular metals used in experiments, such as gold, the wide-band limit (WBL) is a particularly efficient choice. In this paper, we investigate the performance of different WBL schemes relative to more sophisticated approaches including the fully self-consistent non-equilibrium Green's function method. We find reasonably good agreement between all schemes for systems in which the molecule (and not the metal-molecule interface) dominates the transport properties. Moreover, our implementation of the WBL requires negligible computational effort compared to the ground-state density-functional theory calculation of a molecular junction. We also present a new approximate but efficient scheme for calculating transport with a finite bias. Provided the voltage drop occurs primarily inside the molecule, this method provides results in reasonable agreement with fully self-consistent calculations.

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“…Solomon et al also confirmed that the long linearly conjugated molecule is more conductive than the short cross-conjugated one. 43 They attributed this observation to the alternate singledouble bond structure in linearly conjugated molecule. From these facts, we can propose that the electron transport should be more efficient in those conjugated chains with alternate double and single bonds, such as polyacetylene.…”

Section: The Electron Transport Pathwaymentioning

confidence: 99%

Nonequilibrium Green’s function study on the electronic structure and transportation behavior of the conjugated molecular junction: Terminal connections and intramolecular connections

Zhao

et al. 2009

The Journal of Chemical Physics

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In the recent density functional-based calculations, it was found that the conductivity of naphthalene molecular wires can be modulated by altering the linking position of the molecule to the electrode ͓D. Walter, D. Neuhauser, and R. Baer, Chem. Phys. 299, 139 ͑2004͔͒. A quantum interference model was proposed to interpret the observation. In this paper, we further studied the conductance of a series of conjugated molecules containing aromatic rings using density functional theory combined with nonequilibrium Green's function method. For polyacene systems with different terminal connections, the conductivity is dependent on the substitution position of anchoring groups even with similar electron transport distance. The conductance of trans-substitution can be ten times or more as large as that of the cis-substitution. However, for the biphenyl system with different intramolecular connections, adding more connections between two benzene rings does not change the junction conductance. All these results indicate that the junction conductance is strongly dependent on the particular electron transport pathway. The alternating double-single linkage is the most probable one, since others are impeded by the single bonds.

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Understanding quantum interference in coherent molecular conduction

Cited by 256 publications

References 38 publications

A quantum circuit rule for interference effects in single-molecule electrical junctions

A quantum circuit rule for interference effects in single-molecule electrical junctions

Applicability of the wide-band limit in DFT-based molecular transport calculations

Nonequilibrium Green’s function study on the electronic structure and transportation behavior of the conjugated molecular junction: Terminal connections and intramolecular connections

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