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Oz A, Nitzan A, Hod O, Peralta JE. Electron Dynamics in Open Quantum Systems: The Driven Liouville-von Neumann Methodology within Time-Dependent Density Functional Theory. J Chem Theory Comput 2023; 19:7496-7504. [PMID: 37852250 PMCID: PMC10653109 DOI: 10.1021/acs.jctc.3c00311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Indexed: 10/20/2023]
Abstract
A first-principles approach to describe electron dynamics in open quantum systems driven far from equilibrium via external time-dependent stimuli is introduced. Within this approach, the driven Liouville-von Neumann methodology is used to impose open boundary conditions on finite model systems whose dynamics is described using time-dependent density functional theory. As a proof of concept, the developed methodology is applied to simple spin-compensated model systems, including a hydrogen chain and a graphitic molecular junction. Good agreement between steady-state total currents obtained via direct propagation and those obtained from the self-consistent solution of the corresponding Sylvester equation indicates the validity of the implementation. The capability of the new computational approach to analyze, from first principles, non-equilibrium dynamics of open quantum systems in terms of temporally and spatially resolved current densities is demonstrated. Future extensions of the approach toward the description of dynamical magnetization and decoherence effects are briefly discussed.
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Affiliation(s)
- Annabelle Oz
- Department
of Physical Chemistry, School of Chemistry, the Raymond and Beverly
Sackler Faculty of Exact Sciences, and the Sackler Center for Computational
Molecular and Materials Science, Tel Aviv
University, Tel Aviv, 6997801, Israel
| | - Abraham Nitzan
- Department
of Physical Chemistry, School of Chemistry, the Raymond and Beverly
Sackler Faculty of Exact Sciences, and the Sackler Center for Computational
Molecular and Materials Science, Tel Aviv
University, Tel Aviv, 6997801, Israel
- Department
of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19103, United States
| | - Oded Hod
- Department
of Physical Chemistry, School of Chemistry, the Raymond and Beverly
Sackler Faculty of Exact Sciences, and the Sackler Center for Computational
Molecular and Materials Science, Tel Aviv
University, Tel Aviv, 6997801, Israel
| | - Juan E. Peralta
- Department
of Physics, Central Michigan University, Mount Pleasant, Michigan 48859, United States
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2
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Erpenbeck A, Ke Y, Peskin U, Thoss M. How an electrical current can stabilize a molecular nanojunction. NANOSCALE 2023; 15:16333-16343. [PMID: 37766513 DOI: 10.1039/d3nr02176a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/29/2023]
Abstract
The stability of molecular junctions under transport is of the utmost importance for the field of molecular electronics. This question is often addressed within the paradigm of current-induced heating of nuclear degrees of freedom or current-induced forces acting upon the nuclei. At the same time, an essential characteristic of the failure of a molecular electronic device is its changing conductance - typically from a finite value for the intact device to zero for a device that lost its functionality. In this publication, we focus on the current-induced changes in the molecular conductance, which are inherent to molecular junctions at the limit of mechanical stability. We employ a numerically exact framework based on the hierarchical equations of motion approach, which treats both electronic and nuclear degrees of freedom on an equal footing and does not impose additional assumptions. Studying generic model systems for molecular junctions with dissociative potentials for a wide range of parameters spanning the adiabatic and the nonadiabatic regime, we find that molecular junctions that exhibit a decrease in conductance upon dissociation are more stable than junctions that are more conducting in their dissociated state. This represents a new mechanism that stabilizes molecular junctions under current. Moreover, we identify characteristic signatures in the current of breaking junctions related to the interplay between changes in the conductance and the nuclear configuration and show how these are related to properties of the leads rather than characteristics of the molecule itself.
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Affiliation(s)
- André Erpenbeck
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA.
| | - Yaling Ke
- Institute of Physics, University of Freiburg, Hermann-Herder-Strasse 3, 79104 Freiburg, Germany
| | - Uri Peskin
- Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Michael Thoss
- Institute of Physics, University of Freiburg, Hermann-Herder-Strasse 3, 79104 Freiburg, Germany
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3
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Tuovinen R, van Leeuwen R, Perfetto E, Stefanucci G. Electronic transport in molecular junctions: The generalized Kadanoff-Baym ansatz with initial contact and correlations. J Chem Phys 2021; 154:094104. [PMID: 33685185 DOI: 10.1063/5.0040685] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The generalized Kadanoff-Baym ansatz (GKBA) offers a computationally inexpensive approach to simulate out-of-equilibrium quantum systems within the framework of nonequilibrium Green's functions. For finite systems, the limitation of neglecting initial correlations in the conventional GKBA approach has recently been overcome [Karlsson et al., Phys. Rev. B 98, 115148 (2018)]. However, in the context of quantum transport, the contacted nature of the initial state, i.e., a junction connected to bulk leads, requires a further extension of the GKBA approach. In this work, we lay down a GKBA scheme that includes initial correlations in a partition-free setting. In practice, this means that the equilibration of the initially correlated and contacted molecular junction can be separated from the real-time evolution. The information about the contacted initial state is included in the out-of-equilibrium calculation via explicit evaluation of the memory integral for the embedding self-energy, which can be performed without affecting the computational scaling with the simulation time and system size. We demonstrate the developed method in carbon-based molecular junctions, where we study the role of electron correlations in transient current signatures.
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Affiliation(s)
- Riku Tuovinen
- QTF Centre of Excellence, Turku Centre for Quantum Physics, Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland
| | - Robert van Leeuwen
- Department of Physics, Nanoscience Center, University of Jyväskylä, 40014 Jyväskylä, Finland
| | - Enrico Perfetto
- Dipartimento di Fisica, Università di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome, Italy
| | - Gianluca Stefanucci
- Dipartimento di Fisica, Università di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome, Italy
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4
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Brand J, Leitherer S, Papior NR, Néel N, Lei Y, Brandbyge M, Kröger J. Nonequilibrium Bond Forces in Single-Molecule Junctions. NANO LETTERS 2019; 19:7845-7851. [PMID: 31556298 DOI: 10.1021/acs.nanolett.9b02845] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Passing a current across two touching C60 molecules imposes a nonequilibrium population of bonding and antibonding molecular orbitals, which changes the equilibrium bond character and strength. A current-induced bond force therefore contributes to the total force at chemical-bond distances. The combination of first-principles calculations with scanning probe experiments exploring currents and forces in a wide C60-C60 distance range consistently evidences the presence of current-induced attraction that occurs when the two molecules are on the verge of forming a chemical bond. The unique opportunity to arrange matter at the atomic scale with the atomic force and scanning tunneling microscope tip has enabled closely matching molecular junctions in theory and experiment. The findings consequently represent the first report of current-induced bond forces at the single-molecule level and further elucidate the intimate relation between charge transport and force. The results are relevant to molecular electronics and chemical reactions in the presence of a current.
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Affiliation(s)
- Jonathan Brand
- Institut für Physik , Technische Universität Ilmenau , D-98693 Ilmenau , Germany
| | - Susanne Leitherer
- Center for Nanostructured Graphene, Department of Physics , Technical University of Denmark , DK-2800 Kongens Lyngby , Denmark
| | - Nick R Papior
- Department of Applied Mathematics and Computer Science , Technical University of Denmark , DK-2800 Kongens Lyngby , Denmark
| | - Nicolas Néel
- Institut für Physik , Technische Universität Ilmenau , D-98693 Ilmenau , Germany
| | - Yong Lei
- Institut für Physik , Technische Universität Ilmenau , D-98693 Ilmenau , Germany
| | - Mads Brandbyge
- Center for Nanostructured Graphene, Department of Physics , Technical University of Denmark , DK-2800 Kongens Lyngby , Denmark
| | - Jörg Kröger
- Institut für Physik , Technische Universität Ilmenau , D-98693 Ilmenau , Germany
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5
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Tuovinen R, Sentef MA, Gomes da Rocha C, Ferreira MS. Time-resolved impurity-invisibility in graphene nanoribbons. NANOSCALE 2019; 11:12296-12304. [PMID: 31211315 DOI: 10.1039/c9nr02738f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We investigate time-resolved charge transport through graphene nanoribbons supplemented with adsorbed impurity atoms. Depending on the location of the impurities with respect to the hexagonal carbon lattice, the transport properties of the system may become invisible to the impurity due to the symmetry properties of the binding mechanism. This motivates a chemical sensing device since dopants affecting the underlying sublattice symmetry of the pristine graphene nanoribbon introduce scattering. Using the time-dependent Landauer-Büttiker formalism, we extend the stationary current-voltage picture to the transient regime, where we observe how the impurity invisibility takes place at sub-picosecond time scales further motivating ultrafast sensor technology. We further characterize time-dependent local charge and current profiles within the nanoribbons, and we identify rearrangements of the current pathways through the nanoribbons due to the impurities. We finally study the behavior of the transients with ac driving which provides another way of identifying the lattice-symmetry breaking caused by the impurities.
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Affiliation(s)
- Riku Tuovinen
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany.
| | - Michael A Sentef
- Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany.
| | - Claudia Gomes da Rocha
- Department of Physics and Astronomy, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Mauro S Ferreira
- School of Physics, Trinity College Dublin, Dublin 2, Ireland and Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN) and Advanced Materials and Bioengineering Research (AMBER) Centre, Trinity College Dublin, Dublin 2, Ireland
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6
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Pototzky KJ, Zacarias A, Gross EKU. Controlling observables in normal, hybrid and Josephson junctions. Mol Phys 2018. [DOI: 10.1080/00268976.2018.1503746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- K. J. Pototzky
- Max Planck Institute of Microstructure Physics, Halle (Saale), Germany
| | - A. Zacarias
- Max Planck Institute of Microstructure Physics, Halle (Saale), Germany
| | - E. K. U. Gross
- Max Planck Institute of Microstructure Physics, Halle (Saale), Germany
- Chemistry Department, The Hebrew University of Jerusalem, Jerusalem, Israel
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7
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Kurth S, Stefanucci G. Transport through correlated systems with density functional theory. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:413002. [PMID: 28684662 DOI: 10.1088/1361-648x/aa7e36] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We present recent advances in density functional theory (DFT) for applications in the field of quantum transport, with particular emphasis on transport through strongly correlated systems. We review the foundations of the popular Landauer-Büttiker(LB) + DFT approach. This formalism, when using approximations to the exchange-correlation (xc) potential with steps at integer occupation, correctly captures the Kondo plateau in the zero bias conductance at zero temperature but completely fails to capture the transition to the Coulomb blockade (CB) regime as the temperature increases. To overcome the limitations of LB + DFT, the quantum transport problem is treated from a time-dependent (TD) perspective using TDDFT, an exact framework to deal with nonequilibrium situations. The steady-state limit of TDDFT shows that in addition to an xc potential in the junction, there also exists an xc correction to the applied bias. Open shell molecules in the CB regime provide the most striking examples of the importance of the xc bias correction. Using the Anderson model as guidance we estimate these corrections in the limit of zero bias. For the general case we put forward a steady-state DFT which is based on one-to-one correspondence between the pair of basic variables, steady density on and steady current across the junction and the pair local potential on and bias across the junction. Like TDDFT, this framework also leads to both an xc potential in the junction and an xc correction to the bias. Unlike TDDFT, these potentials are independent of history. We highlight the universal features of both xc potential and xc bias corrections for junctions in the CB regime and provide an accurate parametrization for the Anderson model at arbitrary temperatures and interaction strengths, thus providing a unified DFT description for both Kondo and CB regimes and the transition between them.
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Affiliation(s)
- S Kurth
- Nano-Bio Spectroscopy Group and European Theoretical Spectroscopy Facility (ETSF), Dpto. de Física de Materiales, Universidad del País Vasco UPV/EHU, Av. Tolosa 72, E-20018 San Sebastián, Spain. IKERBASQUE, Basque Foundation for Science, Maria Diaz de Haro 3, E-48013 Bilbao, Spain. Author to whom any correspondence should be addressed
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8
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Wang H, Thoss M. On the accuracy of the noninteracting electron approximation for vibrationally coupled electron transport. Chem Phys 2016. [DOI: 10.1016/j.chemphys.2016.06.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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9
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Hyldgaard P. Nonequilibrium thermodynamics of interacting tunneling transport: variational grand potential, density functional formulation and nature of steady-state forces. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:424219. [PMID: 23032101 DOI: 10.1088/0953-8984/24/42/424219] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The standard formulation of tunneling transport rests on an open-boundary modeling. There, conserving approximations to nonequilibrium Green function or quantum statistical mechanics provide consistent but computational costly approaches; alternatively, the use of density-dependent ballistic-transport calculations (e.g., Lang 1995 Phys. Rev. B 52 5335), here denoted 'DBT', provides computationally efficient (approximate) atomistic characterizations of the electron behavior but has until now lacked a formal justification. This paper presents an exact, variational nonequilibrium thermodynamic theory for fully interacting tunneling and provides a rigorous foundation for frozen-nuclei DBT calculations as a lowest-order approximation to an exact nonequilibrium thermodynamic density functional evaluation. The theory starts from the complete electron nonequilibrium quantum statistical mechanics and I identify the operator for the nonequilibrium Gibbs free energy which, generally, must be treated as an implicit solution of the fully interacting many-body dynamics. I demonstrate a minimal property of a functional for the nonequilibrium thermodynamic grand potential which thus uniquely identifies the solution as the exact nonequilibrium density matrix. I also show that the uniqueness-of-density proof from a closely related Lippmann-Schwinger collision density functional theory (Hyldgaard 2008 Phys. Rev. B 78 165109) makes it possible to express the variational nonequilibrium thermodynamic description as a single-particle formulation based on universal electron-density functionals; the full nonequilibrium single-particle formulation improves the DBT method, for example, by a more refined account of Gibbs free energy effects. I illustrate a formal evaluation of the zero-temperature thermodynamic grand potential value which I find is closely related to the variation in the scattering phase shifts and hence to Friedel density oscillations. This paper also discusses the difference between the here-presented exact thermodynamic forces and the often-used electrostatic forces. Finally the paper documents an inherent adiabatic nature of the thermodynamic forces and observes that these are suited for a nonequilibrium implementation of the Born-Oppenheimer approximation.
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Affiliation(s)
- P Hyldgaard
- Department of Microtechnology and Nanoscience, MC2, Chalmers University of Technology, SE-41296 Gothenburg, Sweden.
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10
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Todorović M, Bowler DR. Non-adiabatic simulations of current-related structural transformations in metallic nanodevices. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:345301. [PMID: 21841225 DOI: 10.1088/0953-8984/23/34/345301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
One of the less explored aspects of molecular electronics is the effect of current on the mechanical stability of the conducting molecule: charge flow can alter both the geometry and electronic properties of the device, modifying the conductance and giving rise to nonlinear conduction characteristics or conductance switching. We performed a fundamental study on the correlation between the geometry and evolving electronic structure of small Au clusters that were embedded in finite Au wires and subjected to periodic transient currents. Both the current-carrying electronic states and the local electronic structure of the model system were described away from the ground state within a time-dependent Ehrenfest formalism. Non-adiabatic molecular dynamics simulations revealed that clusters undergo structural transformations between several representative geometries that coincide with patterns in cluster charging. The shape changes were enabled by the fluctuations in cluster band filling associated with the current and assisted by current-related forces. Metastable configurations of stable clusters were linked to events of charge trapping on the cluster.
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Affiliation(s)
- M Todorović
- Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, E-28049 Madrid, Spain
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11
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Dzhioev AA, Kosov DS. Kramers problem for nonequilibrium current-induced chemical reactions. J Chem Phys 2011; 135:074701. [DOI: 10.1063/1.3626521] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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12
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Pacheco AB, Iyengar SS. Multistageab initioquantum wavepacket dynamics for electronic structure and dynamics in open systems: Momentum representation, coupled electron-nuclear dynamics, and external fields. J Chem Phys 2011; 134:074107. [DOI: 10.1063/1.3534797] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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13
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Pacheco AB, Iyengar SS. A multistageab initioquantum wavepacket dynamics formalism for electronic structure and dynamics in open systems. J Chem Phys 2010; 133:044105. [DOI: 10.1063/1.3463798] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Alexander B. Pacheco
- Department of Chemistry and Department of Physics, Indiana University, Bloomington, Indiana 47405, USA
| | - Srinivasan S. Iyengar
- Department of Chemistry and Department of Physics, Indiana University, Bloomington, Indiana 47405, USA
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14
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Kurth S, Stefanucci G, Khosravi E, Verdozzi C, Gross EKU. Dynamical Coulomb blockade and the derivative discontinuity of time-dependent density functional theory. PHYSICAL REVIEW LETTERS 2010; 104:236801. [PMID: 20867260 DOI: 10.1103/physrevlett.104.236801] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Indexed: 05/29/2023]
Abstract
The role of the discontinuity of the exchange-correlation potential of density functional theory is studied in the context of electron transport and shown to be intimately related to Coulomb blockade. By following the time evolution of an interacting nanojunction attached to biased leads, we find that, instead of evolving to a steady state, the system reaches a dynamical state characterized by correlation-induced current oscillations. Our results establish a dynamical picture of Coulomb blockade manifesting itself as a periodic sequence of charging and discharging of the nanostructure.
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Affiliation(s)
- S Kurth
- Nano-Bio Spectroscopy Group, Departamento de Física de Materiales, Universidad del País Vasco UPV/EHU, Centro Física de Materiales CSIC-UPV/EHU, Avenida Tolosa 72, E-20018 San Sebastián, Spain
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15
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Lü JT, Brandbyge M, Hedegård P. Blowing the fuse: Berry's phase and runaway vibrations in molecular conductors. NANO LETTERS 2010; 10:1657-63. [PMID: 20380442 DOI: 10.1021/nl904233u] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
We examine a molecular bridge connecting two metallic electrodes. We find that an electronic current passing across the bridge can cause a vibrational instability of the molecule, which ultimately can lead to a breakdown of the bridge. This instability is generated by a hitherto never considered mechanism, which surprisingly involves the quantum mechanical phase of the electronic waves, the "Berry phase". This mechanism works for highly conducting bridges, and contrary to breakdown by traditional Joule heating, this instability is deterministic and occurs at certain critical voltages. We demonstrate the new mechanism using state-of-the-art ab initio calculations on realistic molecular bridges.
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Affiliation(s)
- Jing-Tao Lü
- DTU Nanotech, Department of Micro and Nanotechnology, Technical University of Denmark, Ørsteds Plads, Building 345E, Kongens Lyngby, Denmark.
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16
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Verstraete MJ, Bokes P, Godby RW. First-principles conductance of nanoscale junctions from the polarizability of finite systems. J Chem Phys 2009; 130:124715. [DOI: 10.1063/1.3096912] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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17
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Dundas D, McEniry EJ, Todorov TN. Current-driven atomic waterwheels. NATURE NANOTECHNOLOGY 2009; 4:99-102. [PMID: 19197311 DOI: 10.1038/nnano.2008.411] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2008] [Accepted: 12/03/2008] [Indexed: 05/07/2023]
Abstract
A current induces forces on atoms inside the conductor that carries it. It is now possible to compute these forces from scratch, and to perform dynamical simulations of the atomic motion under current. One reason for this interest is that current can be a destructive force--it can cause atoms to migrate, resulting in damage and in the eventual failure of the conductor. But one can also ask, can current be made to do useful work on atoms? In particular, can an atomic-scale motor be driven by electrical current, as it can be by other mechanisms? For this to be possible, the current-induced forces on a suitable rotor must be non-conservative, so that net work can be done per revolution. Here we show that current-induced forces in atomic wires are not conservative and that they can be used, in principle, to drive an atomic-scale waterwheel.
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18
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Lü JT, Wang JS. Coupled electron-phonon transport from molecular dynamics with quantum baths. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:025503. [PMID: 21813980 DOI: 10.1088/0953-8984/21/2/025503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Based on generalized quantum Langevin equations for the tight-binding wavefunction amplitudes and lattice displacements, electron and phonon quantum transport are obtained exactly using molecular dynamics (MD) in the ballistic regime. The electron-phonon interactions can be handled with a quasi-classical approximation. Both charge and energy transport and their interplay can be studied. We compare the MD results with those of a fully quantum mechanical nonequilibrium Green's function (NEGF) approach for the electron currents. We find a ballistic to diffusive transition of the electron conduction in one-dimensional chains as the chain length increases.
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19
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Galperin M, Nitzan A, Ratner MA. The non-linear response of molecular junctions: the polaron model revisited. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2008; 20:374107. [PMID: 21694414 DOI: 10.1088/0953-8984/20/37/374107] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A polaron model proposed as a possible mechanism for non-linear conductance (Galperin et al 2005 Nano Lett. 5 125-30) is revisited with the focus on the differences between the weak and strong molecule-lead coupling cases. Within the one-molecule-level model we present an approximate expression for the electronic Green function corresponding to the inelastic transport case, which in the appropriate limits reduces to expressions presented previously for the isolated molecule and for a molecular junction coupled to a slow vibration (static limit). The relevance of considerations based on the isolated molecule limit to understanding properties of molecular junctions is discussed.
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Affiliation(s)
- Michael Galperin
- Theoretical Division and Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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20
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Stefanucci G, Kurth S, Gross E, Rubio A. Chapter 10 Time-dependent transport phenomena. THEORETICAL AND COMPUTATIONAL CHEMISTRY 2007. [DOI: 10.1016/s1380-7323(07)80028-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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