| 1. |
- Andersson, Per H., et al.
(författare)
-
Theoretical study of structural and electronic properties of VHx
- 1998
-
Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 58:9, s. 5230-5235
-
Tidskriftsartikel (refereegranskat)abstract
- We have calculated the change in the electronic structure and the distortion of the lattice in vanadium upon hydrogenation from first principles using the full-potential linear muffin-tin-orbital method and the linear augmented plane-wave method in the local-density approximation. The calculated hydrogen induced volume expansions agree with experiment and the change in the c/a ratio is also in good agreement with observations where such are available for single phase VHx. Among several changes in the electronic structure, we note a hybridization of the d band of vanadium with the hydrogen 1s band. We also observe an antiferromagnetically ordered moment at V/Vexp=1.08. The possibility of producing magnetic V by means of hydrogenation in combination with epitaxial growth is suggested.
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- Fransson, Jonas, et al.
(författare)
-
On the non-orthogonality problem in the description of quantum devices
- 1999
-
Ingår i: Physica. B, Condensed matter. - 0921-4526 .- 1873-2135. ; 272:1-4, s. 28-30
-
Tidskriftsartikel (refereegranskat)abstract
- An approach which allows to include the corrections from non-orthogonality of electron states in contacts and quantum dots is developed. Comparison of the energy levels and charge distributions of electrons in 1D quantum dot (QD) in equilibrium, obtained within orthogonal (OR) and non-orthogonal representations (NOR), with the exact ones shows that the NOR provides a considerable improvement, for levels below the top of barrier. The approach is extended to non-equilibrium states. A derivation of the tunneling current through a single potential barrier is performed using equations of motion for correlation functions. A formula for transient current derived by means of the diagram technique for Hubbard operators is given for the problem of QD with strongly correlated electrons interacting with electrons in contacts. The non-orthogonality renormalizes the tunneling matrix elements and spectral weights of Green functions.
|
|
| 6. |
|
|
| 7. |
- Hugosson, Håkan Wilhelm, 1972-, et al.
(författare)
-
Theoretical studies of substitutional impurities in molybdenum carbide
- 1999
-
Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 60:22, s. 15123-15130
-
Tidskriftsartikel (refereegranskat)abstract
- First-principles full-potential linear muffin-tin orbital calculations have been used to study the effect on the cohesion and electronic structure of cubic δ-MoC when 25% of the carbon is substituted for boron, nitrogen, or oxygen and when 25% of the molybdenum is substituted for niobium, tungsten, or ruthenium. A thorough study of the changes in the electronic structure and the effect of these on the properties of the compounds is made. Special attention is paid to the character (ionic, covalent, or metallic) of the states becoming occupied (or unoccupied) due to the substitution. A study is also made on the properties of the quaternary alloy Mo0.75W0.25C0.75N0.25. This substitution is shown to harden δ-MoC.
|
|
| 8. |
|
|
| 9. |
- Hugosson, Håkan Wilhelm, 1972-, et al.
(författare)
-
Theory of phase stabilities and bonding mechanisms in stoichiometric and substoichiometric molybdenum carbide
- 1999
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 86:7, s. 3758-3767
-
Tidskriftsartikel (refereegranskat)abstract
- ABSTRACTFirst principles, total energy methods have been applied to predict the relative stabilities of the four experimentally verified MoC phases: the cubic δ(NaCl) phase and the three hexagonal γ(WC), η and γ′(TiAs) phases. The effect of vacancies on the relative stability of these four phases was investigated using a model structure with ordered vacancies within the carbon sublattice. For stoichiometric MoC, the γ phase was found to be the most stable followed by γ′, δ, and η, but for substoichiometric MoC0.75,MoC0.75, the order of relative stability was changed and the substoichiometric δ phase was found to have the lowest energy followed by γ′ and γ. A study of the electronic structure revealed vacancy induced peaks in the density of state and the electron density attached to these peaks was analyzed and found to emanate from unscreened Mo–Mo bonds through the carbon vacancy site. Finally, the oxygen stabilization of the γ′ MoC phase was studied.
|
|
| 10. |
- Johansson, Börje, et al.
(författare)
-
A Schloss Laxenburg Model of Product Cycles
- 1998
-
Ingår i: Knowledge and networks in a dynamic economy. - Berlin : Springer. - 3540642455
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
|
|
