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Bengone, Oliver
Alternative names
Publications (6 of 6) Show all publications
Fransson, J., Bengone, O. M., Larsson, J. A. & Greer, J. C. (2006). A physical compact model for electron transport across single molecules. IEEE transactions on nanotechnology, 5(6), 745-749
Open this publication in new window or tab >>A physical compact model for electron transport across single molecules
2006 (English)In: IEEE transactions on nanotechnology, ISSN 1536-125X, E-ISSN 1941-0085, Vol. 5, no 6, p. 745-749Article in journal (Refereed) Published
Abstract [en]

Prediction of current flow across single molecules requires ab initio electronic structure calculations along with their associated high computational demand, and a means for incorporating open system boundary conditions to describe the voltage sources driving the current. To date, first principle predictions of electron transport across single molecules have not fully achieved a predictive capability. The situation for molecular electronics may be compared to conventional technology computer-aided design (TCAD), whereby various approximations to the Boltzmann transport equation are solved to predict electronic device behavior, but in practice are too time consuming for most circuit design applications. To simplify device models for circuit design, analytical but physically motivated models are introduced to capture the behavior of active and passive devices; however, similar models do not vet exist for molecular electronics. We follow a similar approach by evaluating an analytical model achieved by combining a mesoscopic transport model with parameterizations taken from quantum chemical calculations of the electronic structure of single molecule bonded between two metal contacts. Using the model to describe electron transport across benzene- 1,4-dithiol and by comparing to experiment, we are able to extract the coupling strength of the molecule attached to two infinite metal electrodes. The resulting procedure allows for accurate and computationally efficient modeling of the static (dc) characteristics of a single molecule, with the added capability of being able to study the physical model parameter variations across a range of experiments. Such simple physical models are also an important step towards developing a design methodology for molecular electronics.

Keywords
ab initio calculations; density functional theory; molecular electronics; multiphysics modeling; multiscale simulations; nanosystems; transport
National Category
Natural Sciences
Identifiers
urn:nbn:se:miun:diva-10273 (URN)10.1109/TNANO.2006.883485 (DOI)000242840200018 ()
Note
VR-Materials ScienceAvailable from: 2009-11-02 Created: 2009-11-02 Last updated: 2017-12-12Bibliographically approved
Bengone, O., Eriksson, O., Fransson, J., Turek, I., Kudrnovsky, J. & Drchal, V. (2004). Electronic structure and transport properties of CrAs/GaAs/CrAs trilayers from first principles theory. Physical Review B. Condensed Matter and Materials Physics, 70(3), 035302
Open this publication in new window or tab >>Electronic structure and transport properties of CrAs/GaAs/CrAs trilayers from first principles theory
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2004 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 70, no 3, p. 035302-Article in journal (Refereed) Published
Abstract [en]

We present a theoretical study of the transport properties of a CrAs/GaAs/CrAs trilayer. The theory was based on a first principles method for calculating the electronic structure, in combination with a Kubo-Landauer approach for calculating the transport properties in a current perpendicular to the plane geometry. We have also investigated the electronic structure and the magnetic properties of this trilayer, with special focus on electronic and magnetic properties at the CrAs/GaAs interface. Finally, we have studied the effects of chemical disorder on the transport properties, in particular the influence of As antisites at both the Cr and Ga sites.

Identifiers
urn:nbn:se:miun:diva-13498 (URN)10.1103/PhysRevB.70.035302 (DOI)000222996700065 ()
Available from: 2011-04-08 Created: 2011-04-08 Last updated: 2017-12-11Bibliographically approved
Wessley, O., Roy, P., Åberg, D., Andersson, C., Edvardsson, S., Karis, O., . . . Eriksson, O. (2004). Final state effects in the X-ray absorption spectra of La0.7Sr0.3MnO3. Journal of Magnetism and Magnetic Materials, 272-276(3), 1780-1781
Open this publication in new window or tab >>Final state effects in the X-ray absorption spectra of La0.7Sr0.3MnO3
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2004 (English)In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, Vol. 272-276, no 3, p. 1780-1781Article in journal (Refereed) Published
Abstract [en]

We present a comparison of theoretical calculations of the electronic structure of La0.7Sr0.3MnO3 with measurements of the unoccupied local density of states for Mn obtained from X-ray absorption spectroscopy (XAS). We compare two different theoretical calculations of the Mn XAS spectra, one based on the local spin density approximation (LSDA) and the other one based on an atomic Hartree–Fock calculation for the Mn ions. In the atomic calculation the solid state effects are introduced through a cubic crystal field where the crystal field strength is obtained from the LSDA calculation. It is found that the atomic calculations agree better with experimental data.

Keywords
magnetic materials
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:miun:diva-2877 (URN)10.1016/j.jmmm.2003.12.747 (DOI)2516 (Local ID)2516 (Archive number)2516 (OAI)
Available from: 2008-09-30 Created: 2008-09-30 Last updated: 2011-04-04Bibliographically approved
Le Bacq, O., Pasturel, A. & Bengone, O. (2004). Impact on electronic correlations on the structural stability, magnetism, and voltage of LiCoPO4 battery. Physical Review B. Condensed Matter and Materials Physics, 69(24), 245107
Open this publication in new window or tab >>Impact on electronic correlations on the structural stability, magnetism, and voltage of LiCoPO4 battery
2004 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 69, no 24, p. 245107-Article in journal (Refereed) Published
Abstract [en]

We present a study of the structural stability of the lithium-orthophosphate oxide LiCoPO4 using density-functional theory within the local-density (LDA), generalized gradient and LDA+U approximation. We show that both enhanced localization and anisotropic effects provided within the LDA+U approximation are essential to reproduce the experimentally observed magnetic structure, lattice parameters, and stability of the lithiated and nonlithiated compound. Within this approximation, the intercalation voltage of 4.6 eV as well as the insulator character of the lithiated and nonlithiated compounds are recovered. Moreover, we found that the LDA+U approximation induces a strong transfer of charge from the t(2g)-like to the e(g)-like orbitals of Co as well as a significant shift of the LiPO4 band. Both effects are competing with each other and determine most of the peculiar properties of the LiCoPO4 and CoPO4 compounds.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:miun:diva-13501 (URN)10.1103/PhysRevB.69.245107 (DOI)000222531800022 ()
Available from: 2011-04-08 Created: 2011-04-08 Last updated: 2017-12-11Bibliographically approved
Bengone, O., Eriksson, O., Mirbt, S., Turek, I., Kudrnovsky, J. & Drchal, V. (2004). Origin of the negative giant magnetoresistance effect in Co1-xCrx/Cu/Co (111) trilayers. Physical Review B. Condensed Matter and Materials Physics, 69(9), 092406
Open this publication in new window or tab >>Origin of the negative giant magnetoresistance effect in Co1-xCrx/Cu/Co (111) trilayers
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2004 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 69, no 9, p. 092406-Article in journal (Refereed) Published
Abstract [en]

We present a theoretical study on Co1-xCrx/Cu/Co (111) trilayers, where a transition from positive to negative giant magnetoresistance effect has been observed experimentally, with increasing thickness of the alloyed layer. The theory, based on a recently implemented conductance calculation, reproduces quantitatively this observation, and the effect is found to be caused by alloying effects, due to a virtual bound Cr d state in the majority spin channel of the Co-Cr layer.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:miun:diva-13504 (URN)10.1103/PhysRevB.69.092406 (DOI)000220812800017 ()
Available from: 2011-04-08 Created: 2011-04-08 Last updated: 2017-12-11Bibliographically approved
Wessely, O., Roy, P., Åberg, D., Andersson, C., Edvardsson, S., Karis, O., . . . Eriksson, O. (2003). Initial and final state effects in the x-ray absorption process of La1-xSrxMnO3. Physical Review B : Condensed Matter and Materials Physics, 68(23), 235109-1
Open this publication in new window or tab >>Initial and final state effects in the x-ray absorption process of La1-xSrxMnO3
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2003 (English)In: Physical Review B : Condensed Matter and Materials Physics, ISSN 1098-0121, Vol. 68, no 23, p. 235109-1Article in journal (Refereed) Published
Abstract [en]

We have probed the electronic structure of La1-xSrxMnO3 using x-ray absorption spectroscopy, and compared our results to theory. It is shown that the O projected spectrum reveals a signal that is consistent only with hybridized and delocalized Mn d-states whereas the Mn projected spectrum reveals a signal that can only be reproduced by atomic like theory allowing for multiplet formation between the core hole and the valence electrons of the final state. Our results indicate that the ground state electronic structure has delocalized Mn d-states. This is discussed to be caused by a dynamical screening of the core hole created in the absorption process.

Keywords
dft, rare-earth
National Category
Natural Sciences
Identifiers
urn:nbn:se:miun:diva-1822 (URN)10.1103/PhysRevB.68.235109 (DOI)000188186400036 ()581 (Local ID)581 (Archive number)581 (OAI)
Available from: 2008-09-30 Created: 2008-09-30 Last updated: 2011-07-08Bibliographically approved
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