| 751. |
- Nyström, Kristina
(författare)
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Entry and Exit in Swedish Industrial Sectors
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis consists of five individual essays and an introductory chapter. The essays are all in the field of industrial dynamics and more specifically focus on firm entry and exit in Swedish industrial sectors. The essays mainly contribute to the empirical literature on entry and exit. In four of the five essays, panel data methods are used in the empirical investigation. The first essay presents the patterns of entry and exit in industrial sectors in Sweden and studies the importance of different determinants of entry and exit rates in industries. The second essay focuses on the relationship between entry and exit. The third essay has a regional perspective, focusing on regional determinants of entry and exit. It also investigates the importance of the differences in industry structure for differences in entry and exit rates across regions. The fourth chapter uses the theory of product life cycle to investigate how knowledge intensity differs in entering and exiting firms in different stages of the product life cycle. The fifth and last essay focuses on the importance of firm demography, in terms of firm size and age, for the decision to perform process R&D, product R&D or combine process with product R&D.
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| 752. |
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| 753. |
- Odell, Anders, 1979-, et al.
(författare)
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Comparison between s- and d-electron mediated transport in a photoswitching dithienylethene molecule using ab initio transport methods
- 2011
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 84:16, s. 165402-
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Tidskriftsartikel (refereegranskat)abstract
- The influence of the electrode's Fermi surface on the transport properties of a photoswitching molecule is investigated with state-of-the-art ab initio transport methods. We report results for the conducting properties of the two forms of dithienylethene attached either to Ag or to nonmagnetic Ni leads. The I-V curves of the Ag/dithienylethene/Ag device are found to be very similar to those reported previously for Au. In contrast, when Ni is used as the electrode material the zero-bias transmission coefficient is profoundly different as a result of the role played by the Ni d bands in the bonding between the molecule and the electrodes. Intriguingly, despite these differences the overall conducting properties depend little on the electrode material. We thus conclude that electron transport in dithienylethene is, for the cases studied, mainly governed by the intrinsic electronic structure of the molecule.
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| 754. |
- Odell, Anders, et al.
(författare)
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Geometric integration in Born-Oppenheimer molecular dynamics
- 2011
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 135:22, s. 224105-
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Tidskriftsartikel (refereegranskat)abstract
- Geometric integration schemes for extended Lagrangian self-consistent Born-Oppenheimer moleculardynamics, including a weak dissipation to remove numerical noise, are developed and analyzed.The extended Lagrangian framework enables the geometric integration of both the nuclear and electronicdegrees of freedom. This provides highly efficient simulations that are stable and energy conservingeven under incomplete and approximate self-consistent field (SCF) convergence. We investigatethree different geometric integration schemes: (1) regular time reversible Verlet, (2) secondorder optimal symplectic, and (3) third order optimal symplectic. We look at energy conservation,accuracy, and stability as a function of dissipation, integration time step, and SCF convergence. Wefind that the inclusion of dissipation in the symplectic integration methods gives an efficient dampingof numerical noise or perturbations that otherwise may accumulate from finite arithmetics in aperfect reversible dynamics.
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| 755. |
- Odell, Anders, 1979-, et al.
(författare)
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Geometric integration in extended lagrangian self consistent tight-binding molecular dynamics
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Geometric integration schemes for extended Lagrangian self-consistent tight-binding molecular dynamics, including a weak dissipation to remove numerical noise, are developed and analyzed. The extended Lagrangian framework enables the geometric integration of both the nuclear andelectronic degrees of freedom. This provides highly effcient simulations that are stable and energy conserving even under incomplete and approximate self-consistent field (SCF) convergence. We investigate three different geometric integration schemes: i) regular time reversible Verlet, ii) secondorder optimal symplectic, and iii) third order optimal symplectic. We look at energy conservation, accuracy and stabilitty as a function of dissipation, integration time step, and SCF convergence. We find that the inclusion of dissipation in the symplectic integration methods gives an efficient damping of numerical noise or perturbations that otherwise may accumulate from finite arithmetics in a perfect reversible dynamics. The modification of the integration breakes symplecticity and introduces a global energy drift. The systematic drift in energy and the broken symplecticity can be kept arbitrarily small without significant perturbations of the molecular trajectories. However, we have yet to find a formalism for the inclusion of the dissipation in higher-order symplectic integration methods with a more optimal balance between efficient damping and minimal global energy drift.
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| 756. |
- Odell, Anders, et al.
(författare)
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Higher-order symplectic integration in Born-Oppenheimer molecular dynamics
- 2009
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 131:24
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Tidskriftsartikel (refereegranskat)abstract
- The extended Lagrangian formulation of time-reversible Born-Oppenheimer molecular dynamics [A. M. N. Niklasson, C. J. Tymczak, and M. Challacombe, Phys. Rev. Lett. 100, 123004 (2008); Phys. Rev. Lett. 97, 123001 (2006)] enables the use of geometric integrators in the propagation of both the nuclear and the electronic degrees of freedom on the Born-Oppenheimer potential energy surface. Different symplectic integrators up to the sixth order have been adapted and optimized in the framework of ab initio self-consistent-field theory. It is shown how the accuracy can be significantly improved compared to a conventional Verlet integration at the same level of computational cost, in particular, for the case of very high accuracy requirements.
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| 757. |
- Odell, Anders, et al.
(författare)
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Investigation of the Conducting Properties of a Photoswitching Dithienylethene Molecule
- 2010
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Ingår i: ACS NANO. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 4:5, s. 2635-2642
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Tidskriftsartikel (refereegranskat)abstract
- Photoswitching molecules are attractive candidates as organic materials for optoelectronics applications because light impulses can switch them between states with different conducting characteristics. Here, we report a fully self-consistent density functional theory calculation of the electron transport properties of photoswitching dithienylethene attached to Au leads in both the open and closed conformations. The molecule is found to be a good conductor in both conformations, with the low-bias current for the closed one being about 20 times larger than that of the open. Importantly, the current voltage characteristics away from the linear response are largely determined by molecular orbital rehybridization in an electric field, in close analogy to what happens for Mn-12 molecules. However, in the case of dithienylethene attached to Au, such a mechanism is effective also in conditions of strong electronic coupling to the electrodes. This makes the dithienylethene family an intriguing materials platform for constructing highly conducting organic optoelectronics switches.
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| 758. |
- Olovsson, W., et al.
(författare)
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Auger energy shifts in fcc AgPd random alloys from complete screening picture and experiment
- 2004
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 92:22
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Tidskriftsartikel (refereegranskat)abstract
- The Augerkinetic energyand Augerparameter shiftsin fccAgPdrandomalloyswere calculated by extending the completescreeningpicture. The augerkinetic energyshiftfor the L3M4,5M4,5 Auger transition was calculated ab initio and compared with first-principles calculations. The shifts were analyzed as a function of alloy compositions. The Auger kinetic energy shifts were also analyzed in terms of single-hole states for the 2p3/2 core level and double-hole states for the 3d 5/2 core level.
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| 759. |
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| 760. |
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