The Experts below are selected from a list of 147 Experts worldwide ranked by ideXlab platform
L Hedin - One of the best experts on this subject based on the ideXlab platform.
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Theory of spin-polarized Optical Potential.
Journal of synchrotron radiation, 2001Co-Authors: K Hatada, H Tanaka, T Fujikawa, L HedinAbstract:We develop an approximation for the non-local spin-polarized Optical Potential theory for atoms in solids at intermediate and high energy. The present approximation for the Optical Potential builds on the GW-expression. We separate the RPA polarization propagator into a core electron and a valence electron part, and can then achieve a corresponding separation of the Optical Potential. For the valence electron Optical Potential we use a local density approximation because the charge density changes fairly slowly, whereas we use a non-local Optical Potential for the core electron part. Both of them depend on the spin-polarization. We apply this method to electron-Fe elastic scattering in solid, and discuss the results.
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Theoretical study of the non-local Optical Potential in EXAFS spectra.
Journal of Synchrotron Radiation, 2001Co-Authors: K Hatada, T Fujikawa, L HedinAbstract:We study the Optical Potential effects on the extended x-ray absorption fine structure (EXAFS) and x-ray photoelectron diffraction (XPD) spectra. For the valence electron Optical Potential we use a local density approximation because the charge density changes fairly slowly, whereas we use a non-local Optical Potential for the core electron part based on GW-approximation. In the Br K-edge EXAFS spectra the present Optical Potential gives rise to the phase difference and the amplitude reduction; the agreement with the experimental result is excellent. In the N-1s XPD spectra for N2/Ni(100), the spherical wave effects enhance the effects due to the Optical Potential.
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A self-consistent Optical Potential theory for atoms in solids
Journal of Electron Spectroscopy and Related Phenomena, 1998Co-Authors: T Fujikawa, K Hatada, Tetsuro Yikegaki, L HedinAbstract:We develop an approximation for the Optical Potential in a solid, valid at intermediate energies, i.e. energies greater than 50 eV. The present approximation for the Optical Potential builds on the GW-expression. We separate the RPA polarization propagator into a core electron and a valence electron, and can then achieve a corresponding separation of the Optical Potential. We apply this method to electron-Ne and -Ar elastic scatterings and find a satisfactory agreement with the observed results. We also study the importance of self-consistency and the sensitivity to a parameter, the average excitation energy.
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New Approach to the Theory of Atomic Optical Potential in Solids
Japanese Journal of Applied Physics, 1993Co-Authors: T Fujikawa, Akira Saito, L HedinAbstract:We develop an approximation for the Optical Potential in a solid valid at intermediate energies, say energies from some 50 eV and larger. The importance of good Optical Potentials at these energies is clear from experimental and theoretical work on elastic electron-atom scattering. We cannot however directly take over free-atom Potentials for use in a solid. For one thing the valence electrons are largely reorganized when the atom is placed in a solid. One also has to consider the screening effects in solids. Our approximation for the Optical Potential builds on the GW-expression. We separate the RPA polarization propagator in a core electron and a valence electron part, and can then achieve a corresponding separation of the Optical Potential.
T Fujikawa - One of the best experts on this subject based on the ideXlab platform.
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Theory of spin-polarized Optical Potential.
Journal of synchrotron radiation, 2001Co-Authors: K Hatada, H Tanaka, T Fujikawa, L HedinAbstract:We develop an approximation for the non-local spin-polarized Optical Potential theory for atoms in solids at intermediate and high energy. The present approximation for the Optical Potential builds on the GW-expression. We separate the RPA polarization propagator into a core electron and a valence electron part, and can then achieve a corresponding separation of the Optical Potential. For the valence electron Optical Potential we use a local density approximation because the charge density changes fairly slowly, whereas we use a non-local Optical Potential for the core electron part. Both of them depend on the spin-polarization. We apply this method to electron-Fe elastic scattering in solid, and discuss the results.
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Theoretical study of the non-local Optical Potential in EXAFS spectra.
Journal of Synchrotron Radiation, 2001Co-Authors: K Hatada, T Fujikawa, L HedinAbstract:We study the Optical Potential effects on the extended x-ray absorption fine structure (EXAFS) and x-ray photoelectron diffraction (XPD) spectra. For the valence electron Optical Potential we use a local density approximation because the charge density changes fairly slowly, whereas we use a non-local Optical Potential for the core electron part based on GW-approximation. In the Br K-edge EXAFS spectra the present Optical Potential gives rise to the phase difference and the amplitude reduction; the agreement with the experimental result is excellent. In the N-1s XPD spectra for N2/Ni(100), the spherical wave effects enhance the effects due to the Optical Potential.
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A self-consistent Optical Potential theory for atoms in solids
Journal of Electron Spectroscopy and Related Phenomena, 1998Co-Authors: T Fujikawa, K Hatada, Tetsuro Yikegaki, L HedinAbstract:We develop an approximation for the Optical Potential in a solid, valid at intermediate energies, i.e. energies greater than 50 eV. The present approximation for the Optical Potential builds on the GW-expression. We separate the RPA polarization propagator into a core electron and a valence electron, and can then achieve a corresponding separation of the Optical Potential. We apply this method to electron-Ne and -Ar elastic scatterings and find a satisfactory agreement with the observed results. We also study the importance of self-consistency and the sensitivity to a parameter, the average excitation energy.
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New Approach to the Theory of Atomic Optical Potential in Solids
Japanese Journal of Applied Physics, 1993Co-Authors: T Fujikawa, Akira Saito, L HedinAbstract:We develop an approximation for the Optical Potential in a solid valid at intermediate energies, say energies from some 50 eV and larger. The importance of good Optical Potentials at these energies is clear from experimental and theoretical work on elastic electron-atom scattering. We cannot however directly take over free-atom Potentials for use in a solid. For one thing the valence electrons are largely reorganized when the atom is placed in a solid. One also has to consider the screening effects in solids. Our approximation for the Optical Potential builds on the GW-expression. We separate the RPA polarization propagator in a core electron and a valence electron part, and can then achieve a corresponding separation of the Optical Potential.
K Hatada - One of the best experts on this subject based on the ideXlab platform.
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Theory of spin-polarized Optical Potential.
Journal of synchrotron radiation, 2001Co-Authors: K Hatada, H Tanaka, T Fujikawa, L HedinAbstract:We develop an approximation for the non-local spin-polarized Optical Potential theory for atoms in solids at intermediate and high energy. The present approximation for the Optical Potential builds on the GW-expression. We separate the RPA polarization propagator into a core electron and a valence electron part, and can then achieve a corresponding separation of the Optical Potential. For the valence electron Optical Potential we use a local density approximation because the charge density changes fairly slowly, whereas we use a non-local Optical Potential for the core electron part. Both of them depend on the spin-polarization. We apply this method to electron-Fe elastic scattering in solid, and discuss the results.
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Theoretical study of the non-local Optical Potential in EXAFS spectra.
Journal of Synchrotron Radiation, 2001Co-Authors: K Hatada, T Fujikawa, L HedinAbstract:We study the Optical Potential effects on the extended x-ray absorption fine structure (EXAFS) and x-ray photoelectron diffraction (XPD) spectra. For the valence electron Optical Potential we use a local density approximation because the charge density changes fairly slowly, whereas we use a non-local Optical Potential for the core electron part based on GW-approximation. In the Br K-edge EXAFS spectra the present Optical Potential gives rise to the phase difference and the amplitude reduction; the agreement with the experimental result is excellent. In the N-1s XPD spectra for N2/Ni(100), the spherical wave effects enhance the effects due to the Optical Potential.
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A self-consistent Optical Potential theory for atoms in solids
Journal of Electron Spectroscopy and Related Phenomena, 1998Co-Authors: T Fujikawa, K Hatada, Tetsuro Yikegaki, L HedinAbstract:We develop an approximation for the Optical Potential in a solid, valid at intermediate energies, i.e. energies greater than 50 eV. The present approximation for the Optical Potential builds on the GW-expression. We separate the RPA polarization propagator into a core electron and a valence electron, and can then achieve a corresponding separation of the Optical Potential. We apply this method to electron-Ne and -Ar elastic scatterings and find a satisfactory agreement with the observed results. We also study the importance of self-consistency and the sensitivity to a parameter, the average excitation energy.
M Johnson - One of the best experts on this subject based on the ideXlab platform.
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s wave pion Optical Potential from medium modified ππ scattering amplitude
Physics Letters B, 1993Co-Authors: C Schutz, K Holinde, J Speth, M JohnsonAbstract:Abstract We show that a recent model of medium modifications of the ππ scattering amplitude leads to a new source of repulsion in the S-wave pion Optical Potential, which existing models are unable to explain. Our result indicates that pions do not condense through S-wave interactions.
Jacques Tempere - One of the best experts on this subject based on the ideXlab platform.
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Competition between the FuldeFerrellLarkinOvchinnikov phase and the BardeenCooper Schrieffer phase in the presence of an Optical Potential
Journal of Physics B: Atomic Molecular and Optical Physics, 2011Co-Authors: Jeroen P A Devreese, Michiel Wouters, Jacques TempereAbstract:In three dimensional Fermi gases with spin imbalance, a competition exists between Cooper pairing with zero and with finite momentum. The latter gives rise to the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superfluid phase, which only exists in a restricted area of the phase diagram as a function of chemical Potential imbalance and interaction strength. Applying an Optical Potential along one direction enhances the FFLO region in this phase diagram. In this paper, we construct the phase diagram as a function of polarization and interaction strength in order to study the competition between the FFLO phase and the spin balanced BCS phase. This allows to take into account the region of phase separation, and provides a more direct connection with experiment. Subsequently, we investigate the effects of the wavelength and the depth of the Optical Potential, which is applied along one direction, on the FFLO state. It is shown that the FFLO state can exist up to a higher level of spin imbalance if the wavelength of the Optical Potential becomes smaller. Our results give rise to an interesting effect: the maximal polarization at which the FFLO state can exist, decreases when the interaction strength exceeds a certain critical value. This counterintuitive phenomenon is discussed and the connection to the Optical Potential is explained.
