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  • 1.
    Brandbyge, Mads
    et al.
    Tech Univ Denmark.
    Frederiksen, Thomas
    DIPC, San Sebastian 20018, Spain.
    Paulsson, Magnus
    University of Kalmar, School of Pure and Applied Natural Sciences.
    DFT-NEGF approach to current-induced forces, vibrational signals, and heating in nanoconductors2009In: Current-Driven Phenomena in Nanoelectronics / [ed] T. Seideman, Pan Stanford Publishing, 2009, p. 90-122Chapter in book (Other academic)
  • 2. Brandbyge, Mads
    et al.
    Frederiksen, Thomas
    Paulsson, Magnus
    University of Kalmar, School of Pure and Applied Natural Sciences.
    First-principles NEGF-DFT transport2006In: Report on multiscale approaches to modelling for nanotechnology / [ed] M. Macucci, S. Roche, A. Correia, 2006Chapter in book (Other academic)
  • 3. Damle, Prashant
    et al.
    Rakshit, Titash
    Paulsson, Magnus
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Datta, Supriyo
    Current-voltage characteristics of molecular conductors: Two versus three terminal2002In: IEEE TRANSACTIONS ON NANOTECHNOLOGY, Vol. 1Article in journal (Refereed)
  • 4.
    Frederiksen, T.
    et al.
    Donostia Int Phys Ctr DIPC UPV EHU, San Sebastian 20018, Spain.
    Paulsson, Magnus
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering. Toyama Univ, Grad Sch Sci & Engn, Div Nano & New Funct Mat Sci, Toyama 930855, Japan.
    Ueba, H.
    Toyama Univ, Grad Sch Sci & Engn, Div Nano & New Funct Mat Sci, Toyama 930855, Japan.
    Theory of action spectroscopy for single-molecule reactions induced by vibrational excitations with STM2014In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 89, no 3, p. 035427-Article in journal (Refereed)
    Abstract [en]

    A theory of action spectroscopy, i.e., a reaction rate or yield as a function of bias voltage, is presented for single-molecule reactions induced by the inelastic tunneling current with a scanning tunneling microscope. A formula for the reaction yield is derived using the adsorbate resonance model, which provides a versatile tool to analyze vibrationally mediated reactions of single adsorbates on conductive surfaces. This allows us to determine the energy quantum of the excited vibrational mode, the effective broadening of the vibrational density of states (as described by Gaussian or Lorentzian functions), and a prefactor characterizing the elementary process behind the reaction. The underlying approximations are critically discussed. We point out that observation of reaction yields at both bias voltage polarities can provide additional insight into the adsorbate density of states near the Fermi level. As an example, we apply the theory to the case of flip motion of a hydroxyl dimer (OD)(2) on Cu(110) which was experimentally observed by Kumagai et al. [Phys. Rev. B 79, 035423 (2009)]. In combination with density functional theory calculations for the vibrational modes, the vibrational damping due to electron-hole pair generation, and the potential energy landscape for the flip motion, a detailed microscopic picture for the switching process is established. This picture reveals that the predominant mechanism is excitation of the OD stretch modes which couple anharmonically to the low-energy frustrated rotation mode.

  • 5. Frederiksen, Thomas
    et al.
    Lorente, Nicolas
    Paulsson, Magnus
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Brandbyge, Mads
    From tunneling to contact: Inelastic signals in an atomic gold junction from first principles2007In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 75, no 23, article id 235441Article in journal (Refereed)
  • 6. Frederiksen, Thomas
    et al.
    Munuera, C
    Ocal, C
    Brandbyge, Mads
    Paulsson, Magnus
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Sanches-Portal, D
    Arnau, A
    Exploring the Tilt-Angle Dependence of Electron Tunneling across Molecular Junctions of Self-Assembled Alkanethiols2009In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 3, no 8, p. 2073-2080Article in journal (Refereed)
    Abstract [en]

    Electronic transport mechanisms in molecular junctions are investigated by a combination of first-principles calculations and current-voltage measurements of several well-characterized structures. We study self-assembled layers of alkanethiols grown on Au(111) and form tunnel junctions by contacting the molecular layers with the tip of a conductive force microscope. Measurements done under low-load conditions permit us to obtain reliable tilt-angle and molecular length dependencies of the low-bias conductance through the alkanethiol layers. The observed dependence on tilt-angle is stronger for the longer molecular chains. Our calculations confirm the observed trends and explain them as a result of two mechanisms, namely, a previously proposed intermolecular tunneling enhancement as well as a hitherto overlooked tilt-dependent molecular gate effect.

  • 7. Frederiksen, Thomas
    et al.
    Paulsson, Magnus
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Brandbyge, Mads
    Inelastic Finger-prints of Hydrogen Contamination in Atomic Gold Wire Systems2007Conference paper (Refereed)
  • 8. Frederiksen, Thomas
    et al.
    Paulsson, Magnus
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Brandbyge, Mads
    Jauho, Antti-Pekka
    Inelastic transport theory from first principles: Methodology and application to nanoscale devices2007In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 75, no 20, article id 205413Article in journal (Refereed)
  • 9. Frederiksen, Thomas
    et al.
    Paulsson, Magnus
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Brandbyge, Mads
    Jauho, A.-P.
    First-principles theory of inelastic transport and local heating in atomic gold wires2007In: AIP Conf. Proc. 893, 2007Conference paper (Refereed)
  • 10.
    Gustafsson, Alexander
    et al.
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Okabayashi, Norio
    Kanazawa Univ, Japan ; Univ Regensburg, Germany.
    Peronio, Angelo
    Univ Regensburg, Germany.
    Giessibl, Franz J.
    Univ Regensburg, Germany.
    Paulsson, Magnus
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Analysis of STM images with pure and CO-functionalized tips: A first-principles and experimental study2017In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 96, no 8, article id 085415Article in journal (Refereed)
    Abstract [en]

    We describe a first-principles method to calculate scanning tunneling microscopy (STM) images, and compare the results to well-characterized experiments combining STM with atomic force microscopy (AFM). The theory is based on density functional theory with a localized basis set, where the wave functions in the vacuum gap are computed by propagating the localized-basis wave functions into the gap using a real-space grid. Constant-height STM images are computed using Bardeen's approximation method, including averaging over the reciprocal space. We consider copper adatoms and single CO molecules adsorbed on Cu(111), scanned with a single-atom copper tip with and without CO functionalization. The calculated images agree with state-of-the-art experiments, where the atomic structure of the tip apex is determined by AFM. The comparison further allows for detailed interpretation of the STM images.

  • 11.
    Gustafsson, Alexander
    et al.
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Paulsson, Magnus
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Scanning tunneling microscopy current from localized basis orbital density functional theory2016In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 93, no 11, article id 115434Article in journal (Refereed)
    Abstract [en]

    We present a method capable of calculating elastic scanning tunneling microscopy (STM) currents from localized atomic orbital density functional theory (DFT). To overcome the poor accuracy of the localized orbital description of the wave functions far away from the atoms, we propagate the wave functions, using the total DFT potential. From the propagated wave functions, the Bardeen's perturbative approach provides the tunneling current. To illustrate the method we investigate carbon monoxide adsorbed on a Cu(111) surface and recover the depression/protrusion observed experimentally with normal/CO-functionalized STM tips. The theory furthermore allows us to discuss the significance of s- and p-wave tips.

  • 12.
    Gustafsson, Alexander
    et al.
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Paulsson, Magnus
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    STM contrast of a CO dimer on a Cu(111) surface: a wave-function analysis2017In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 29, no 505301Article in journal (Refereed)
    Abstract [en]

    We present a method used to intuitively interpret the scanning tunneling microscopy (STM) contrast by investigating individual wave functions originating from the substrate and tip side. We use localized basis orbital density functional theory, and propagate the wave functions into the vacuum region at a real-space grid, including averaging over the lateral reciprocal space. Optimization by means of the method of Lagrange multipliers is implemented to perform a unitary transformation of the wave functions in the middle of the vacuum region. The method enables (i) reduction of the number of contributing tip-substrate wave function combinations used in the corresponding transmission matrix, and (ii) to bundle up wave functions with similar symmetry in the lateral plane, so that (iii) an intuitive understanding of the STM contrast can be achieved. The theory is applied to a CO dimer adsorbed on a Cu(1 1 1) surface scanned by a single-atom Cu tip, whose STM image is discussed in detail by the outlined method.

  • 13.
    Gustafsson, Alexander
    et al.
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Ueba, Hiromu
    Toyama Univ, Japan.
    Paulsson, Magnus
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Theory of vibrationally assisted tunneling for hydroxyl monomer flipping on Cu(110)2014In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 90, no 16, p. Article ID: 165413-Article in journal (Refereed)
    Abstract [en]

    To describe vibrationally mediated configuration changes of adsorbates on surfaces we have developed a theory to calculate both reaction rates and pathways. The method uses the T-matrix to describe excitations of vibrational states by the electrons of the substrate, adsorbate, and tunneling electrons from a scanning tunneling probe. In addition to reaction rates, the theory also provides the reaction pathways by going beyond the harmonic approximation and using the full potential energy surface of the adsorbate which contains local minima corresponding to the adsorbates different configurations. To describe the theory, we reproduce the experimental results in [T. Kumagai et al., Phys. Rev. B 79, 035423 (2009)], where the hydrogen/deuterium atom of an adsorbed hydroxyl (OH/OD) exhibits back and forth flipping between two equivalent configurations on a Cu(110) surface at T = 6 K. We estimate the potential energy surface and the reaction barrier, similar to 160 meV, from DFT calculations. The calculated flipping processes arise from (i) at low bias, tunneling of the hydrogen through the barrier, (ii) intermediate bias, tunneling electrons excite the vibrations increasing the reaction rate although over the barrier processes are rare, and (iii) higher bias, overtone excitations increase the reaction rate further.

  • 14. Hansson, Anders
    et al.
    Paulsson, Magnus
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Stafstrom, Sven
    Effect of bending and vacancies on the conductance of carbon nanotubes2000In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 62, no 11, p. 7639-7644Article in journal (Refereed)
    Abstract [en]

    Electron transport through nanotubes is studied theoretically using the Landauer formalism. The studies are carried out for finite metallic nanotubes that bridge two contacts pads. The current is observed to increase stepwise with the applied voltage. Each step corresponds to resonance tunneling including one single-particle eigenstate of the nanotube. Moderate bending of the nanotube results in a shift of the single-particle levels but the overall current remains essentially unaffected. For large bending, however, the pi electron system becomes more disturbed, which introduces backscattering and a marked decrease in the conductivity along the tube. A single carbon vacancy in the nanotube is shown to have very small effect on the conductivity in the center of the metallic band whereas, by increasing the defect concentration the conductivity decreases in the same way as for the strongly bent tubes.

  • 15. Hayashi, M.
    et al.
    Ootsuka, Y.
    Paulsson, Magnus
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Persson, B.N.J.
    Ueba, Hiromu
    Lateral hopping of CO molecules on Pt(111) surface by femtosecond laser pulses2009In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 80, no Article number: 245409Article in journal (Refereed)
    Abstract [en]

    Theory of heat transfer between adsorbate vibrational degrees of freedom and ultrafast laser heated hot electrons including vibrational intermode coupling is applied to calculate two-pulse correlation, laser fluence dependence and time dependence of lateral hopping of CO molecules from a step to terrace site on a stepped Pt (111) surface. The intermode coupling is a key ingredient to describe vibrational heating of the frustrated translation mode responsible for the CO hopping. The calculated results are in good agreement with the experimental results, especially if we scale down the experimentally determined absorbed fluence. It is found that CO hopping is induced by indirect heating of the FT mode by the FR mode with a strong frictional coupling to hot electrons.

  • 16. Javey, A
    et al.
    Guo, J
    Paulsson, Magnus
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Wang, Q
    Mann, D
    Lundstrom, Mark
    Dai, HJ
    Title: High-field quasiballistic transport in short carbon nanotubes2004In: PHYSICAL REVIEW LETTERS, Vol. 92Article in journal (Refereed)
  • 17.
    Kitaguchi, Y.
    et al.
    Kyoto University, Japan.
    Habuka, S.
    Kyoto University, Japan.
    Okuyama, H.
    Kyoto University, Japan.
    Hatta, S.
    Kyoto University, Japan.
    Aruga, T.
    Kyoto University, Japan.
    Frederiksen, T.
    DIPC, Spain ; Ikerbasque, Spain.
    Paulsson, Magnus
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Ueba, H.
    University of Toyama, Japan.
    Controlling single-molecule junction conductance by molecular interactions2015In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5, article id 11796Article in journal (Refereed)
    Abstract [en]

    For the rational design of single-molecular electronic devices, it is essential to understand environmental effects on the electronic properties of a working molecule. Here we investigate the impact of molecular interactions on the single-molecule conductance by accurately positioning individual molecules on the electrode. To achieve reproducible and precise conductivity measurements, we utilize relatively weak pi-bonding between a phenoxy molecule and a STM-tip to form and cleave one contact to the molecule. The anchoring to the other electrode is kept stable using a chalcogen atom with strong bonding to a Cu(110) substrate. These non-destructive measurements permit us to investigate the variation in single-molecule conductance under different but controlled environmental conditions. Combined with density functional theory calculations, we clarify the role of the electrostatic field in the environmental effect that influences the molecular level alignment.

  • 18.
    Kitaguchi, Yuya
    et al.
    Kyoto University, Japan.
    Habuka, Satoru
    Kyoto University, Japan.
    Okuyama, Hiroshi
    Kyoto University, Japan.
    Hatta, Shinichiro
    Kyoto University, Japan.
    Aruga, Tetsuya
    Kyoto University, Japan.
    Frederiksen, Thomas
    Donostia International Physics Center (DIPC), Spain ; IKERBASQUE, Basque Foundation for Science, Spain.
    Paulsson, Magnus
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Ueba, Hiromu
    University of Toyama, Japan.
    Controlled switching of single-molecule junctions by mechanical motion of a phenyl ring2015In: Beilstein Journal of Nanotechnology, ISSN 2190-4286, Vol. 6, p. 2088-2095Article in journal (Refereed)
    Abstract [en]

    Mechanical methods for single-molecule control have potential for wide application in nanodevices and machines. Here we demonstrate the operation of a single-molecule switch made functional by the motion of a phenyl ring, analogous to the lever in a conventional toggle switch. The switch can be actuated by dual triggers, either by a voltage pulse or by displacement of the electrode, and electronic manipulation of the ring by chemical substitution enables rational control of the on-state conductance. Owing to its simple mechanics, structural robustness, and chemical accessibility, we propose that phenyl rings are promising components in mechanical molecular devices.

  • 19. Koleini, Muhammad
    et al.
    Paulsson, Magnus
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Brandbyge, Mads
    Efficient organometallic spin filter between single-wall carbon nanotube or graphene electrodes2007In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 98Article in journal (Refereed)
  • 20. Kristensen, IS
    et al.
    Paulsson, Magnus
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Thygesen, KS
    Jacobsen, KW
    Inelastic scattering in metal-H-2-metal junctions2009In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 79, no Article number: 235411Article in journal (Refereed)
    Abstract [en]

    We present first-principles calculations of the dI/dV characteristics of an H-2 molecule sandwiched between Au and Pt electrodes in the presence of electron-phonon interactions. The conductance is found to decrease by a few percentages at threshold voltages corresponding to the excitation energy of longitudinal vibrations of the H-2 molecule. In the case of Pt electrodes, the transverse vibrations can mediate transport through otherwise nontransmitting Pt d channels leading to an increase in the differential conductance even though the hydrogen junction is characterized predominately by a single almost fully open transport channel. In the case of Au, the transverse modes do not affect the dI/dV because the Au d states are too far below the Fermi level. A simple explanation of the first-principles results is given using scattering theory. Finally, we compare and discuss our results in relation to experimental data.

  • 21. Liang, GC
    et al.
    Ghosh, Avik
    Paulsson, Magnus
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Datta, Supriyo
    Electrostatic potential profiles of molecular conductors2004In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 69, no 11, article id 115302Article in journal (Refereed)
  • 22.
    Michalak, Lukasz
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Canali, Carlo M.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Pederson, Mark R.
    Navy Research Laboratory, Washington DC, (U.S.A).
    Paulsson, Magnus
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Benza, V.G.
    Universitá dell'Insubria, Como (Italy).
    Theory of tunneling spectroscopy in a Mn12 single-electron transistor by DFT methods2010In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 104, no 1, p. 017202-017205Article in journal (Refereed)
  • 23.
    Okabayashi, Norio
    et al.
    University of Regensburg , Germany ; Kanazawa University, Japan.
    Gustafsson, Alexander
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Peronio, Angelo
    University of Regensburg, Germany.
    Paulsson, Magnus
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Arai, Toyoko
    Kanazawa University, Japan.
    Giessibl, Franz
    University of Regensburg, Germany.
    Influence of atomic tip structure on the intensity of inelastic tunneling spectroscopy data analyzed by combined scanning tunneling spectroscopy, force microscopy, and density functional theory2016In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 93, no 16, article id 165415Article in journal (Refereed)
    Abstract [en]

    Achieving a high intensity in inelastic scanning tunneling spectroscopy (IETS) is important for precise measurements. The intensity of the IETS signal can vary by up to a factor of 3 for various tips without an apparent reason accessible by scanning tunneling microscopy (STM) alone. Here, we show that combining STM and IETS with atomic force microscopy enables carbon monoxide front-atom identification, revealing that high IETS intensities for CO/Cu(111) are obtained for single-atom tips, while the intensity drops sharply for multiatom tips. Adsorption of the CO molecule on a Cu adatom [CO/Cu/Cu(111)] such that the molecule is elevated over the substrate strongly diminishes the tip dependence of IETS intensity, showing that an elevated position channels most of the tunneling current through the CO molecule even for multiatom tips, while a large fraction of the tunneling current bypasses the CO molecule in the case of CO/Cu(111).

  • 24. Okabayashi, Norio
    et al.
    Paulsson, Magnus
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Hiromu, Ueba
    Konda, Youhei
    Komeda, Tadahiro
    Site Selective Inelastic Electron Tunneling Spectroscopy Probed by Isotope Labeling2010In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 10, no 8, p. 2950-2955Article in journal (Refereed)
  • 25.
    Okabayashi, Norio
    et al.
    Kanazawa University.
    Paulsson, Magnus
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Komeda, Tadahiro
    Tohoku University.
    Inelastic electron tunneling process for alkanethiol self-assembled monolayers2013In: Progress in Surface Science, ISSN 0079-6816, E-ISSN 1878-4240, Vol. 88, no 1, p. 1-38Article, review/survey (Refereed)
    Abstract [en]

    Recent investigations of inelastic electron tunneling spectroscopy (IETS) for alkanethiol self-assembled monolayers (SAMs) are reviewed. Alkanethiol SAMs are usually prepared by immersing a gold substrate into a solution of alkanethiol molecules, and they are very stable, even under ambient conditions. Thus, alkanethiol SAMs have been used as typical molecules for research into molecular electronics. Infrared spectroscopy and electron energy loss spectroscopy (EELS) have frequently been employed to characterize SAMs on the macroscopic scale. For characterization of alkanethiol SAMs on the nanometer scale region, or for single alkanethiol molecules through which electrons actually tunnel, IETS has proven to be an effective method. However, IETS experiments for alkanethiol SAMs employing different methods have shown large differences, i.e., there is a lack of standard data for alkanethiol SAMs with which to understand the IET process or to satisfactorily compare with theoretical investigations. An effective means of acquiring standard data is the formation of a tunneling junction with scanning tunneling microscopy (STM). After explanation of the STM experimental techniques, standard IETS data are presented whereby a contact condition between the tip and SAM is tuned. We have found that many vibrational modes are detected by STM-IETS, as is also the case for EELS. These results are compared with LET spectra measured with different tunneling junctions. In order to precisely investigate which vibrational modes are active in IETS, isotope labeling of alkanethiols with specifically synthesized isotopically substituted molecule has been examined. This method provides unambiguous assignments of IET spectra peaks and site selectivity for alkanethiol SAMs such that all parts of the alkanethiol molecules almost equally contribute to the IET process. The LET process is also discussed based on density functional theory and nonequilibrium Green's function calculations. These results quantitatively reproduce many the experimentally observed features, whereas Fermi's golden rule for JETS qualitatively explains the propensity rule and site selectivity observed in the experiments. However, comparison between experiment and theory reveals a large difference in JETS intensity for the C H stretching mode that originates from the side chains of the alkanethiol molecules. In order to explain this difference, we discuss the importance of an intermolecular tunneling process in the SAM. Application of STM-IETS to identify a hydrogenated alkanethiol molecule inserted into a deuterated alkanethiol SAM matrix is also demonstrated. (C) 2012 Elsevier Ltd. All rights reserved.

  • 26. Okabayashi, Norio
    et al.
    Paulsson, Magnus
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Ueba, Hiromu
    Konda, Youhei
    Komeda, Tadahiro
    Inelastic Tunneling Spectroscopy of Alkanethiol Molecules: High-Resolution Spectroscopy and Theoretical Simulations2010In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 104, p. Article ID: 077801-Article in journal (Refereed)
  • 27.
    Okuyama, H
    et al.
    Kyoto University.
    Shiotari, A
    Kyoto University.
    Kumagai, T
    Kyoto University.
    Hatta, S
    Kyoto University.
    Aruga, T
    Kyoto University.
    Ootsuka, Y
    University of Toyama.
    Paulsson, Magnus
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Ueba, H
    University of Toyama.
    Modifying current-voltage characteristics of a single molecule junction by isotope substitution: OHOD dimer on Cu(110)2012In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 85, no 20, p. Article ID: 205424-Article in journal (Refereed)
    Abstract [en]

    Vibrationally induced configurational change and nonlinear current-voltage (I-V) characteristics are investigated within the scanning tunneling microscope (STM) junction, including hydroxyl dimers on a Cu(110) surface. H-bonded hydroxyl dimers composed of OH and/or OD have a unique inclined geometry that can be switched back and forth by vibrational excitations via the inelastic electron tunneling process of the STM. The relative occupation change between the high-and low-conductance states as a function of bias voltage critically depends on the isotopic compositions, and thus the I-V characteristics can be modified to exhibit negative differential resistance by H/D substitution. The experimental results of the occupation change and I-V curves are nicely reproduced using a recently proposed analytical model combined with comprehensive density functional calculations for the input parameters (vibrational modes and their emission rates by tunneling electrons, conductance, and relative occupation change of high-and low-conductance states), and they underlines the different roles played by the free and shared O-H(D) stretch modes of the hydroxyl dimers on a Cu(110) surface.

  • 28.
    Ootsuka, Yasuhiro
    et al.
    Toyama University, Japan.
    Fredersiksen, Thomas
    Donostia Int Phys Ctr, Spain.
    Ueba, Hiromu
    Toyama University, Japan.
    Paulsson, Magnus
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Vibrationally induced flip motion of a hydroxyl dimer on Cu(110)2011In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 84, p. Article ID 193403-Article in journal (Refereed)
  • 29.
    Paulsson, Magnus
    Linkoping University, Department of Physics.
    Electron transport in pi-conjugated systems2001Doctoral thesis, monograph (Other academic)
  • 30.
    Paulsson, Magnus
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Brandbyge, Mads
    Transmission eigenchannels from nonequilibrium Green's functions2007In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 76, no 11, article id 115117Article in journal (Refereed)
  • 31.
    Paulsson, Magnus
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Datta, Supriyo
    Thermoelectric effect in molecular electronics2003In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 67, no 24, p. 2414031-2414034Article in journal (Refereed)
  • 32.
    Paulsson, Magnus
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Frederiksen, Thomas
    Brandbyge, Mads
    Inelastic transport through molecules: Comparing first-principles calculations to experiments2006In: Nano letters, Vol. 6, p. 258-262Article in journal (Refereed)
  • 33.
    Paulsson, Magnus
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Frederiksen, Thomas
    Brandbyge, Mads
    Modeling inelastic phonon scattering in atomic- and molecular-wire junctions2005In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 72, no 20, article id 201101Article in journal (Refereed)
    Abstract [en]

    Computationally inexpensive approximations describing electron-phonon scattering in molecular-scale conductors are derived from the nonequilibrium Green's function method. The accuracy is demonstrated with a first-principles calculation on an atomic gold wire. Quantitative agreement between the full nonequilibrium Green's function calculation and the newly derived expressions is obtained while simplifying the computational burden by several orders of magnitude. In addition, analytical models provide intuitive understanding of the conductance including nonequilibrium heating and provide a convenient way of parameterizing the physics. This is exemplified by fitting the expressions to the experimentally observed conductances through both an atomic gold wire and a hydrogen molecule.

  • 34.
    Paulsson, Magnus
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Frederiksen, Thomas
    Brandbyge, Mads
    Molecular Electronics: Insight from First-Principles Transport Simulations2010In: Chimia (Basel), ISSN 0009-4293, Vol. 64, no 6, p. 350-355Article in journal (Refereed)
  • 35.
    Paulsson, Magnus
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Frederiksen, Thomas
    Brandbyge, Mads
    Phonon scattering in nanoscale systems: Lowest order expansion of the current2006Conference paper (Refereed)
  • 36.
    Paulsson, Magnus
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Frederiksen, Thomas
    Brandbyge, Mads
    Phonon scattering in nanoscale systems: Lowest order expansion of the current and power expressions2006In: J. Phys.: Conf. Series 35, 2006Conference paper (Refereed)
  • 37.
    Paulsson, Magnus
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Frederiksen, Thomas
    Ueba, Hiromu
    Lorente, Nicolas
    Brandbyge, Mads
    Unified Description of Inelastic Propensity Rules for Electron Transport through Nanoscale Junctions2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 100, no 22, p. Article ID: 226604-Article in journal (Refereed)
    Abstract [en]

    We present a method to analyze the results of first-principles based calculations of electronic currents including inelastic electron-phonon effects. This method allows us to determine the electronic and vibrational symmetries in play, and hence to obtain the so-called propensity rules for the studied systems. We show that only a few scattering states—namely those belonging to the most transmitting eigenchannels—need to be considered for a complete description of the electron transport. We apply the method on first-principles calculations of four different systems and obtain the propensity rules in each case.

  • 38.
    Paulsson, Magnus
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Krag, Casper
    Frederiksen, Thomas
    Brandbyge, Mads
    Conductance of Alkanedithiol Single-Molecule Junctions: A Molecular Dynamics Study2009In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 9, no 1, p. 117-121Article in journal (Refereed)
    Abstract [en]

    We study formation and conductance of alkanedithiol junctions using density functional based molecular dynamics. The formation involves straightening of the molecule, migration of thiol end-groups, and pulling out Au atoms. Plateaus are found in the low-bias conductance traces which decrease by 1 order of magnitude when gauche defects are present. We further show that the inelastic electron tunneling spectra depend on the junction geometry. In particular, our simulations suggest ways to identify gauche defects.

  • 39.
    Paulsson, Magnus
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Stafstrom, Sven
    Conductance calculations through stacks of polyaromatic hydrocarbons2001In: SYNTHETIC METALS 121, 2001Conference paper (Refereed)
  • 40.
    Paulsson, Magnus
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Stafstrom, Sven
    Conductance manipulation at the molecular level1999In: JOURNAL OF PHYSICS-CONDENSED MATTER, Vol. 11Article in journal (Refereed)
  • 41.
    Paulsson, Magnus
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Stafstrom, Sven
    Conductance through a C-60 molecule1999In: SYNTHETIC METALS 101, 1999Conference paper (Refereed)
  • 42.
    Paulsson, Magnus
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Stafstrom, Sven
    Effects of doping and interchain interactions on the metal-insulator transition in trans-polyacetylene1999In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 60, no 11, p. 7939-7943Article in journal (Refereed)
  • 43.
    Paulsson, Magnus
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Stafstrom, Sven
    Numerical investigation of electron localization in polymer chains1998In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 57, no 4, p. 2197-2202Article in journal (Refereed)
  • 44.
    Paulsson, Magnus
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Stafstrom, Sven
    Self-consistent-field study of conduction through conjugated molecules2001In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 64, no 3, p. 0354161-03541610Article in journal (Refereed)
  • 45.
    Paulsson, Magnus
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Stafstrom, Sven
    Theoretical study of electron transport along self-assembled graphitic nanowires2000In: JOURNAL OF PHYSICS-CONDENSED MATTER, Vol. 12Article in journal (Refereed)
  • 46. Paulsson, Magnus
    et al.
    Zahid, Ferdows
    Datta, Supriyo
    Resistance of a molecule2003In: Handbook of nanoscience, engineering, and technology / [ed] William A. Goddard III, Donald Brenner, Sergey Edward Lyshevski and Gerald J Iafrate, Boca Raton: CRC Press, 2003, 1, p. 12-1-12-25Chapter in book (Other academic)
  • 47.
    Shchadilova, Yulia E.
    et al.
    Russian Acad Sci.
    Tikhodeev, Sergei G.
    Russian Acad Sci / Toyama Univ.
    Paulsson, Magnus
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering. Toyama Univ.
    Ueba, Hiromu
    Toyama Univ.
    Isotope effect in acetylene C2H2 and C2D2 rotations on Cu(001)2014In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 89, no 16, p. Article ID: 165418-Article in journal (Refereed)
    Abstract [en]

    A comprehensive analysis of the elementary processes behind the scanning tunneling microscope controlled rotation of C2H2 and C2D2, isotopologues of a single acetylene molecule adsorbed on the Cu(001) surface, is given, with a focus on the isotope effects. With the help of density-functional theory we calculate the vibrational modes of C2H2 and C2D2 on Cu(001) and estimate the anharmonic couplings between them, using a simple strings-on-rods model. The probability of the elementary processes, nonlinear and combination band, is estimated using the Keldysh diagram technique. This allows us to clarify the main peculiarities and the isotope effects of the C2H2 and C2D2 on Cu(001) rotation, discovered in the pioneering work [B. C. Stipe et al., Phys. Rev. Lett. 81, 1263 (1998)], which have not been previously understood.

  • 48.
    Shchadilova, Yulia E.
    et al.
    Russian Acad Sci, AM Prokhorov Gen Phys Inst, Moscow 119991, Russia.
    Tikhodeev, Sergei G.
    Russian Acad Sci, AM Prokhorov Gen Phys Inst, Moscow 119991, Russia.
    Paulsson, Magnus
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering. Toyama Univ, Grad Sch Sci & Engn, Div Nanotechnol & New Funct Mat Sci, Toyama 9308555, Japan.
    Ueba, Hiromu
    Toyama Univ, Grad Sch Sci & Engn, Div Nanotechnol & New Funct Mat Sci, Toyama 9308555, Japan.
    Rotation of a Single Acetylene Molecule on Cu(001) by Tunneling Electrons in STM2013In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 111, no 18, p. Article ID:186102-Article in journal (Refereed)
    Abstract [en]

    We study the elementary processes behind one of the pioneering works on scanning tunneling microscope controlled reactions of single molecules [Stipe et al., Phys. Rev. Lett. 81, 1263 (1998)]. Using the Keldysh-Green function approach for the vibrational generation rate in combination with density functional theory calculations to obtain realistic parameters we reproduce the experimental rotation rate of an acetylene molecule on a Cu(100) surface as a function of bias voltage and tunneling current. This combined approach allows us to identify the reaction coordinate mode of the acetylene rotation and its anharmonic coupling with the C-H stretch mode. We show that three different elementary processes, the excitation of C-H stretch, the overtone ladder climbing of the hindered rotational mode, and the combination band excitation together explain the rotation of the acetylene molecule on Cu(100).

  • 49. Ueba, H
    et al.
    Ootsuka, Y
    Paulsson, Magnus
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Persson, BNJ
    Lateral hopping of CO on Cu(111) induced by femtosecond laser pulses2010In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 82, no 12, article id 121411Article in journal (Refereed)
  • 50. Ueba, Hiromu
    et al.
    Hayashi, M
    Paulsson, Magnus
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Persson, B N J
    Adsorbate hopping via vibrational-mode coupling induced by femtosecond laser pulses2008In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 78, p. Article ID: 113408-Article in journal (Refereed)
    Abstract [en]

    We study the heat transfer from femtosecond laser-heated hot electrons in a metal to adsorbates in the presence of vibrational-mode coupling. The theory is successfully applied to the experimental result of atomic oxygen hopping on a vicinal Pt(111) surface. The effective friction coupling between hot electrons and the vibrational mode relevant to the hopping motion depends on the transient temperature of the partner mode excited by hot electrons. The calculated two-pulse correlation and fluence dependence of the hopping probability reproduce the experimental results, which were previously analyzed using the hot-electron temperature (Te)-dependent friction ηa(Te) in a conventional heat transfer equation. A possible elementary process behind such a hypothetic modeling using ηa(Te) is discussed in terms of an indirect heating of the vibrational mode for hopping at the surface.

12 1 - 50 of 55
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