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- Joyce, J. J., et al.
(författare)
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Dual nature of the 5f electrons in plutonium materials
- 2006
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Ingår i: Physica. B, Condensed matter. - : Elsevier BV. - 0921-4526 .- 1873-2135. ; 378-80, s. 920-924
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of select Pu materials is examined by means of photoemission (PES) and model calculations. We present the first photoemission results and electronic structure calculations for the material PuIn3. Results for Pu materials, including the cubic delta-phase metal and the superconductor PuCoGa5, give indication of the 5f electrons exhibiting both localized and itinerant character. These new results for PuIn3 place this compounds also in the 5f dual nature category. The dual nature of the Pu 5f electrons demarks the boundary between localized and itinerant 5f character in the actinides. The photoemission data for delta-Pu, PuIn3 and PuCoGa5 are compared against model calculations. The calculations are a mixed level model (MLM) which is a multi-electron extension of the generalized gradient approximation. Using the MLM, one obtains good agreement for the volume and total energy minimum with 4 of 5 Pu 5f electrons localized. The calculations also agree well with the PES spectra. Other computational schemes and interpretations are also reviewed.
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- Wills, J. M., et al.
(författare)
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A novel electronic configuration of the 5f states in delta-plutonium as revealed by the photo-electron spectra
- 2004
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 135:2-3, s. 163-166
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Tidskriftsartikel (refereegranskat)abstract
- We present a theoretical model, the mixed-level model, aiming at describing metals with very complex, strongly correlated, electronic structures. As a demonstration, it is applied to the electronic structure of delta-Pu. The model reproduces the electronic-structure related properties of this complex metal; in particular, the theory is capable of reproducing the valence band photoemission spectrum of delta-Pu. We also report new experimental photoemission spectra at several photon energies. Taken together, our results provide strong evidence that the electronic structure of delta-Pu involves a 5f shell with four electrons in a localized multiplet hybridizing with valence states, and approximately one 5f electron forming a completely delocalized band state.
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| 10. |
- Lundgren, Edvin, et al.
(författare)
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Geometry of the valence transition induced surface reconstruction of Sm(0001).
- 2002
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 88:13, s. 136102-136102
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Tidskriftsartikel (refereegranskat)abstract
- We present a structural determination of the surface reconstruction of the Sm(0001) surface using surface x-ray diffraction, scanning tunneling microscopy, and ab initio calculations. The reconstruction is associated with a large (22%) expansion of the atomic radius for the top monolayer surface Sm atoms. The mechanism driving the surface reconstruction in Sm is unique among all elements and is connected to the strong correlations of the 4f electrons in Sm and the intermediate valence observed in certain Sm compounds. The atoms constituting the top monolayer of Sm(0001) have vastly different chemical properties compared to the layer underneath and behave as if they were an adsorbate of a different chemical species.
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- Delin, Lovisa, et al.
(författare)
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Challenger - A mobile phone application for treatment of social phobia : A randomized controlled trial of a self-help treatment in book form with or without the addition of mobile phone application
- 2015
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Ingår i: Abstracts from the 7th Swedish Congress on internet interventions (SWEsrii). - Linköping : Linköping University Press. ; , s. 23-23
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Social phobia is one of the most common anxiety disorders. The diagnosis results in great suffering for the individual but also large social costs. This randomized, controlled study (N = 209) aimed to evaluate the relative impact of a self-help treatment in book form, with or without the addition of a mobile phone application for people with social phobia. Results demonstrated a statistically significant greater improvement between the two active treatment groups and the waiting list. A medium-sized effect size on the primary outcome measure Liebowitz Social Anxiety Scale self report was found only between the waiting list and the group treated with the addition of mobile application. Statistically significant differences were not found between the two active treatment groups. The results of this study strengthen previous research which has shown that bibliotherapy is effective for social phobia. Since the research on the efficiency of mobile phone applications for treatment of social phobia are limited, this study contributes to necessary knowledge in the field.
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| 18. |
- 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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| 20. |
- Wills, J. M., et al.
(författare)
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Total Energy and Forces : Some Numerical Examples
- 2010
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Ingår i: Full-Potential Electronic Structure Method. - Berlin, Heidelberg : Springer Nature. ; , s. 101-109
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Bokkapitel (refereegranskat)abstract
- Numerical examples of calculations of total energy, equation of state and Hellman-Feynman forces are given. The calculation of first principles phonons is also exemplified with fcc Al and bcc U. A comparison between a few selected exchange and correlation functionals is also made for the calculation of the equation of state.
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