Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Augmented Planewaves, Developments and Applications to Magnetism
Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics.
2002 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The present thesis concerns method development and applications in the field of first principles electronic structure calculations.

Augmented planewaves combine the simple planewaves with exact solutions of the Schrödinger equation for a spherical potential. This combination yields a very good set of basis functions for describing the electronic structure everywhere in a crystal potential. In the present work, developments of the original augmented planewave (APW) method are presented. It is shown that the exact APW eigenvalues can be found using information from the eigenvalues of the APW secular matrix. This provides a more efficient scheme to solve the APW eigenvalue problem, than the traditional evaluation of the secular determinant. Further, a new way of linearizing the APW method is presented and compared to the traditional linearized APW method (LAPW). Using a combination of the original APW basis functions and the so called local orbitals (lo), the APW+lo linearization is found to reproduce the results of the LAPW method, but already at a smaller basis set size. Another advantage of the new linearization is a faster convergence of forces, with respect to the basis set size, as compared to the LAPW method.

The applications include studies of the non-collinear magnetic configuration in the fcc-based high-temperature phase of iron, γ-Fe. The system is found to be extremely sensitive to volume changes, as well as to a tetragonal distortion of the cubic unit cell. A continuum of degenerate spin spiral configurations, including the global energy minimum, are found for the undistorted crystal. The in-plane anisotropy of the ideal interface between a ferromagnetic layer of bcc Fe and the semiconducting ZnSe crystal is also investigated. In contrast to the four-fold symmetric arrangement of the atoms at the interface, the in-plane magnetic anisotropy displays a large uniaxiality. The calculated easy axes are in agreement with experiments for both Se and Zn terminated interfaces. In addition, calculations of the hyperfine parameters were performed for Li intercalated battery materials.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis , 2002. , p. 67
Series
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-232X ; 701
Keyword [en]
Physics, First principles electronic structure calculations, augmented planewaves, non-collinear magnetism, in-plane magnetic anisortopy, hyperfine parameters
Keyword [sv]
Fysik
National Category
Physical Sciences
Research subject
Physics
Identifiers
URN: urn:nbn:se:uu:diva-1928ISBN: 91-554-5286-8 (print)OAI: oai:DiVA.org:uu-1928DiVA, id: diva2:161511
Public defence
2002-04-26, Polhemssalen, Ångström laboratoriet, Uppsala, 10:15
Opponent
Available from: 2002-04-05 Created: 2002-04-05Bibliographically approved
List of papers
1. Efficient solution of the non-linear APW secular equation
Open this publication in new window or tab >>Efficient solution of the non-linear APW secular equation
(English)In: Journal of Physics: Condensed MatterArticle in journal (Refereed) Submitted
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-89763 (URN)
Available from: 2002-04-05 Created: 2002-04-05 Last updated: 2012-03-29Bibliographically approved
2. An alternative way of linearizing the augmented-plane-wave method
Open this publication in new window or tab >>An alternative way of linearizing the augmented-plane-wave method
2000 (English)In: Solid State Communications, ISSN 0038-1098, E-ISSN 1879-2766, Vol. 114, no 1, p. 15-20Article in journal (Refereed) Published
Abstract [en]

A new basis set for a full potential treatment of crystal electronic structures is presented and compared to that of the well-known linearized augmented plane-wave (LAPW) method. The basis set consists of energy-independent augmented plane-wave functions combined with local orbitals. Each basis function is continuous over the whole unit cell but it may have a discontinuous slope at the muffin-tin boundaries, i.e. at the surfaces of atomic centered, non-overlapping spheres. This alternative way to linearize the augmented plane-wave method is shown to reproduce the accurate results of the LAPW method, but using a smaller basis set size. The reduction in number of basis functions is most significant for open structures.

Keyword
surfaces and interfaces, electronic band structure, molecules, core
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-89764 (URN)10.1016/S0038-1098(99)00577-3 (DOI)
Available from: 2002-04-05 Created: 2002-04-05 Last updated: 2017-12-14Bibliographically approved
3. Efficient linearization of the augmented plane-wave method
Open this publication in new window or tab >>Efficient linearization of the augmented plane-wave method
Show others...
2001 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 64, no 19, p. 195134-Article in journal (Refereed) Published
Abstract [en]

We present a detailed analysis of the APW+lo basis set for band-structure calculations. This basis set consists of energy independent augmented plane-wave (APW) functions. The linearization is introduced through local orbitals evaluated at the same linearization energy as the APW functions. It is shown that results obtained with the APW+lo basis set converge much faster and often more systematically towards the final value. The APW+lo thereby allows accurate treatment of systems that were previously unaccessible to linearized APW. Furthermore, it is shown that APW+lo converges to the same total energy as LAPW provided the higher angular momenta l are linearized, either by adding extra local orbitals or treating them by LAPW. It is illustrated that the APW basis functions are much closer to the true form of the eigenfunctions than the LAPW basis functions. This is especially true for basis functions that have a strong energy dependence inside the sphere.

National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-89765 (URN)10.1103/PhysRevB.64.195134 (DOI)
Available from: 2002-04-05 Created: 2002-04-05 Last updated: 2017-12-14Bibliographically approved
4. Forces in the APW+lo method.
Open this publication in new window or tab >>Forces in the APW+lo method.
(English)Manuscript (Other academic)
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-89766 (URN)
Available from: 2002-04-05 Created: 2002-04-05 Last updated: 2012-03-29Bibliographically approved
5. Hyperfine parameters of η'-Cu6Sn5 and Li2CuSn
Open this publication in new window or tab >>Hyperfine parameters of η'-Cu6Sn5 and Li2CuSn
Show others...
2001 (English)In: Hyperfine Interactions, ISSN 0304-3843, E-ISSN 1572-9540, Vol. 136-137, no 3-8, p. 555-560Article in journal (Refereed) Published
Abstract [en]

η′-Cu6Sn5, a suggested anode material in Li-ion batteries, has been studied by 119Sn Mössbauer spectroscopy together with the lithiated phase Li2CuSn. Full-potential electronic structure calculations were carried out using full potential LAPW (linearized augmented plane wave) within the local density approximation. The calculated hyperfine parameters, isomer shift and electric quadrupole splitting, were compared to the experimental. In presence of more than one Sn-site, the theoretical values provide a good starting guess to fit a single Mössbauer absorption peak to different sites.

National Category
Physical Sciences Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-89767 (URN)10.1023/A:1020531026013 (DOI)
Available from: 2002-04-05 Created: 2002-04-05 Last updated: 2017-12-30
6. A theoretical and experimental study of the lithiation of η'-Cu6Sn5 in a lithium-ion battery
Open this publication in new window or tab >>A theoretical and experimental study of the lithiation of η'-Cu6Sn5 in a lithium-ion battery
Show others...
2003 (English)In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 150, no 3, p. A330-A334Article in journal (Refereed) Published
Abstract [en]

Themechanism of Li insertion in -Cu6Sn5 to form Li2CuSn isdiscussed in detail, based on both theoretical calculations and experimentalresults. The mechanism is investigated by means of first principlescalculations, with the full potential linearized augmented plane wave method,in combination with in situ X-ray diffraction experiments. The -Cu6Sn5structure, as well as its lithiated products, were optimized andthe electronic charge density calculated in order to study thechange in bond character on lithiation. The average insertion voltageof the -Cu6Sn5-Li2CuSn transformation has been calculated to be 0.378V, in good agreement with the experimental value.                            

Keyword
lithium alloys, copper alloys, tin alloys, ab initio calculations, APW calculations, X-ray diffraction, bonds (chemical), secondary cells, electrochemical electrodes
National Category
Physical Sciences Inorganic Chemistry
Identifiers
urn:nbn:se:uu:diva-89768 (URN)10.1149/1.1544634 (DOI)
Available from: 2002-04-05 Created: 2002-04-05 Last updated: 2017-12-30
7. Non-collinear full-potential studies of γ-Fe
Open this publication in new window or tab >>Non-collinear full-potential studies of γ-Fe
(English)In: Phys. Rev. BArticle in journal (Refereed) Submitted
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-89769 (URN)
Available from: 2002-04-05 Created: 2002-04-05 Last updated: 2012-03-29Bibliographically approved
8. Tetragonal distortions of spin spiral states in γ-Fe
Open this publication in new window or tab >>Tetragonal distortions of spin spiral states in γ-Fe
(English)Manuscript (Other academic)
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-89770 (URN)
Available from: 2002-04-05 Created: 2002-04-05 Last updated: 2012-03-29Bibliographically approved
9. Damping within adiabatically calculated spin-wave spectra
Open this publication in new window or tab >>Damping within adiabatically calculated spin-wave spectra
(English)Manuscript (Other academic)
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-89771 (URN)
Available from: 2002-04-05 Created: 2002-04-05 Last updated: 2012-03-29Bibliographically approved
10. Non-collinear magnetization density in VAu4
Open this publication in new window or tab >>Non-collinear magnetization density in VAu4
2002 (English)In: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 90, no 6, p. 1610-1613Article in journal (Refereed) Published
Abstract [en]

The spin and orbital magnetic moments of VAu4 have been calculated using a first principles method that allows for noncollinear magnetic ordering. The large spin–orbit coupling of the Au atom is argued to induce large noncollinear components of the magnetization density as well as a parallel coupling between spin and orbital moments of the V atom, in contrast to expectations from Hund's third rule.

Keyword
noncollinear magnetism; first principles theory; Hund's rules; spin and orbital moments; LAPW
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-89772 (URN)10.1002/qua.10345 (DOI)
Available from: 2002-04-05 Created: 2002-04-05 Last updated: 2017-12-14Bibliographically approved
11. Uniaxial magnetocrystalline anisotropy of metal/semiconductor interfaces: Fe/ZnSe(001)
Open this publication in new window or tab >>Uniaxial magnetocrystalline anisotropy of metal/semiconductor interfaces: Fe/ZnSe(001)
2002 (English)In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 89, no 26, p. 267203-Article in journal (Refereed) Published
Abstract [en]

A theoretical study of the magnetic moments and the in-plane magnetic anisotropy of an interface between a cubic ferromagnet and a cubic semiconductor, Fe/ZnSe(001), is presented. Theory confirms the observed, much debated, uniaxial anisotropy of the iron film. This result is important since the calculations are for perfect interfaces with squarelike environments, proving that the fourfolded symmetry of the interface Fe atoms is broken beyond the nearest neighboring semiconducting layer, effects that are usually assumed small. It is demonstrated how the uniaxial anisotropy is produced by the directional covalent bonds at the interface, even without atomic relaxations.

National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-89773 (URN)10.1103/PhysRevLett.89.267203 (DOI)
Available from: 2002-04-05 Created: 2002-04-05 Last updated: 2017-12-14
12. Magnetic moment and anisotropy at the Fe/ZnSe(001) interface studied by conversion electron Mössbauer spectroscopy
Open this publication in new window or tab >>Magnetic moment and anisotropy at the Fe/ZnSe(001) interface studied by conversion electron Mössbauer spectroscopy
Show others...
2002 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 66, no 2, p. 024405-Article in journal (Refereed) Published
Abstract [en]

The interface magnetic properties of Fe/ZnSe heterostructures grown on GaAs(001) by molecular-beam epitaxy have been investigated using conversion electron Mössbauer spectroscopy (CEMS) and macroscopic magnetic measurements. For Fe films thinner than 100 Å an in-plane 〈110〉 uniaxial magnetic anisotropy was found and the magnetization loops could successfully be described by the simple Stoner-Wohlfarth model, which implies that the magnetization reverses only by coherent rotation and jump processes. For the interface analysis, a 5-Å-thick layer of enriched 57Fe was deposited on the ZnSe surface and buried under 20 Å of natural Fe. In this way the 57Fe serves as a local probe of the interface magnetic environment in a bulklike Fe film since the CEMS technique is only sensitive to this isotope of Fe. An interface magnetic moment of 2.18 μB was found and, in relation to 2.2 μB for bulk bcc Fe, this precludes the presence of any interface reactions. Surprisingly, however, the direction of the interface magnetic moment turned out to be reoriented from the [110] direction by almost 30°, an effect that was assumed to arise from the distribution of unidirectional tetrahedral bonds present on the Zn c(2×2) reconstructed ZnSe surface.

National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-89774 (URN)10.1103/PhysRevB.66.024405 (DOI)
Available from: 2002-04-05 Created: 2002-04-05 Last updated: 2017-12-14Bibliographically approved

Open Access in DiVA

fulltext(2800 kB)1316 downloads
File information
File name FULLTEXT01.pdfFile size 2800 kBChecksum SHA-1
ab2a34609b3644c3d4424b13f10f3bc401fdaede6f5270d865707afdd9bb1d0a797c084c
Type fulltextMimetype application/pdf
Buy this publication >>

By organisation
Department of Physics
Physical Sciences

Search outside of DiVA

GoogleGoogle Scholar
Total: 1316 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 1173 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf