Rate-Dependent Energy Release Mechanism of Gold Nanowires under Elongation

Pu, Qing; Leng, Yongsheng; Cummings, Peter T.

doi:10.1021/ja806319g

Cited by 18 publications

(44 citation statements)

References 38 publications

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“…Note that MACs have been observed in experiments 19,34,35 and in simulations [19][20][21] of elongating Au nanowires without BDT. MACs have also been observed in simulations of thiolate-terminated molecules being pulled away from step edges on Au surfaces 36 and in simulations of Au-alkanedithiolate-Au junctions.…”

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confidence: 75%

Atomistic simulations of highly conductive molecular transport junctions under realistic conditions

French¹,

Iacovella²,

Rungger

et al. 2013

Nanoscale

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We report state-of-the-art atomistic simulations combined with high-fidelity conductance calculations to probe structure-conductance relationships in Au-benzenedithiolate (BDT)-Au junctions under elongation. Our results demonstrate that large increases in conductance are associated with the formation of monatomic chains (MACs) of Au atoms directly connected to BDT. An analysis of the electronic structure of the simulated junctions reveals that enhancement in the s-like states in Au MACs causes the increases in conductance. Other structures also result in increased conductance but are too short-lived to be detected in experiment, while MACs remain stable for long simulation times. Examinations of thermally evolved junctions with and without MACs show negligible overlap between conductance histograms, indicating that the increase in conductance is related to this unique structural change and not thermal fluctuation. These results, which provide an excellent explanation for a recently observed anomalous experimental result [Bruot et al., Nat. Nanotechnol., 2012, 7, 35-40], should aid in the development of mechanically responsive molecular electronic devices.

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confidence: 75%

Atomistic simulations of highly conductive molecular transport junctions under realistic conditions

French¹,

Iacovella²,

Rungger

et al. 2013

Nanoscale

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“…Methods based on classical force fields have also been used to simulate molecular junctions 27-30 and related systems. [35][36][37] Classical force field (CFF) methods (i.e., molecular dynamics -MD -and…”

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confidence: 99%

Large-Scale Atomistic Simulations of Environmental Effects on the Formation and Properties of Molecular Junctions

2012

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Using an updated simulation tool, we examine molecular junctions composed of benzene-1,4-dithiolate bonded between gold nanotips, focusing on the importance of environmental factors and interelectrode distance on the formation and structure of bridged molecules. We investigate the complex relationship between monolayer density and tip separation, finding that the formation of multimolecule junctions is favored at low monolayer density, while single-molecule junctions are favored at high density. We demonstrate that tip geometry and monolayer interactions, two factors that are often neglected in simulation, affect the bonding geometry and tilt angle of bridged molecules. We further show that the structures of bridged molecules at 298 and 77 K are similar.

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“…methods, 7,9,10,12,14,22,24,35,36 requiring a compromise between the accuracy of the interatomic interactions and the accessible system size and timescale. Quantum mechanical methods, such as density functional theory (DFT), are widely considered to provide a highly accurate description of the interactions between Au atoms, in particular, capturing the stability of 2-d planar geometries for low coordination clusters.…”

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confidence: 99%

“…Semi-empirical methods, such as the second-moment approximation of the tight-binding (TB-SMA) scheme, 39 are many orders of magnitude faster than quantum mechanical methods, allowing for the efficient exploration of large numbers of statepoints and systems sizes more representative of experiment. 7,10,12,14 While methods such as TB-SMA have been shown to qualitatively match the behavior of experiment in side-by-side studies, 7 semi-emperical methods are often fitted to bulk systems, and thus may produce results that are quantitatively inconsistent with theory or experiment, 41 especially for low coordination atomic-scale contacts. 38,40 In particular, the minimal energy 2-d planar structures of Au are not typically stable for semi-empirical methods 38 which may incorrectly bias NW simulations towards forming 3-d isomers.…”

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Role of Polytetrahedral Structures in the Elongation and Rupture of Gold Nanowires

Iacovella

French²,

Cook³

et al. 2011

ACS Nano

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We report comprehensive high-accuracy molecular dynamics simulations using the ReaxFF force field to explore the structural changes that occur as Au nanowires are elongated, establishing trends as a function of both temperature and nanowire diameter. Our simulations and subsequent quantitative structural analysis reveal that polytetrahedral structures (e.g., icosahedra) form within the "amorphous" neck regions, most prominently for systems with small diameter at high temperature. We demonstrate that the formation of polytetrahedra diminishes the conductance quantization as compared to systems without this structural motif. We demonstrate that use of the ReaxFF force field, fitted to high-accuracy first-principles calculations of Au, combines the accuracy of quantum calculations with the speed of semiempirical methods.

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Rate-Dependent Energy Release Mechanism of Gold Nanowires under Elongation

Cited by 18 publications

References 38 publications

Atomistic simulations of highly conductive molecular transport junctions under realistic conditions

Atomistic simulations of highly conductive molecular transport junctions under realistic conditions

Large-Scale Atomistic Simulations of Environmental Effects on the Formation and Properties of Molecular Junctions

Role of Polytetrahedral Structures in the Elongation and Rupture of Gold Nanowires

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