liu.seSearch for publications in DiVA
Change search
ReferencesLink to record
Permanent link

Direct link
Electronic and atomic structure of Mo from high-temperature molecular dynamics simulations
Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
Applied Materials Physics, Department of Material Science and Engineering, The Royal Institute of Technology, 10044 Stockholm, Swedent.
Linköping University, Department of Computer and Information Science, Statistics. Linköping University, The Institute of Technology.
Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
(English)Manuscript (preprint) (Other (popular science, discussion, etc.))
Abstract [en]

By means of ab initio molecular dynamics (AIMD) simulations we carry out a detailed stdly of the electronic and atomic structure of Mo upon the thermal stabilization of its dynamically unstable face-centered cubic (fcc) phase, Wc calculate how the atomic positions, radial distribution function, and the ei<xtronic density of states of fcc Mo evolve with temperature. The results are compared with those for dynamically stable body-centered cubic (bcc) phase of Mo, as well as with bcc Zr, which is dynamically unstable at T = OK, but (in contrast to fcc Mo) becomes thermodynamically stable at high temperature, In particular, wc emphasize the difference between the local positions of atoms in the simulation boxes at a particular step of AIMD simulation and the average positions, around which the atoms vibrate, and show that the former are solcly responsible for the electronic properties of the material. WE observe that while the average atomic positions in fcc Mo correspond perfectly to the ideal structure at high temperature, the electronic structure of the metal calculated from AIMD differs substantially from the canonical shape of the density of states for the ideal fcc crystaL From a comparison of our results obtained for fcc Mo arid bcc Zr, we advocate the use of the electronic structure calculations, complemented with studies of radial distribution functions, as a sensitive test of a degree of the temperature induced stabilization of phases, which are dynamically unstable at T = OK.

URN: urn:nbn:se:liu:diva-53779OAI: diva2:291828
Available from: 2010-02-03 Created: 2010-02-03 Last updated: 2010-02-11
In thesis
1. Effects of disorder in metallic systems from First-Principles calculations
Open this publication in new window or tab >>Effects of disorder in metallic systems from First-Principles calculations
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis, quantum-mechanical calculations within density-functional theory on metallic systems are presented. The overarching goal has been to investigate effects of disorder. In particular, one of the properties investigated is the bindingenergy shifts for core electrons in binary alloys using different theoretical methods. These methods are compared with each other and with experimental results. One such method, the so-called Slater-Janak transition state method relies on the assumption that the single-particle eigenvalues within density-functional theory are linear functions of their respective occupation number. This assumption is investigated and it is found that while the eigenvalues to a first approximation show linear behavior, there are also nonlinearities which can influence the core-level binding energy shifts.

Another area of investigation has been iron based alloys at pressures corresponding to those in the Earth’s inner core. This has been done for the hexagonal close packed and face entered cubic structures. The effects of alloying iron with magnesium and nickel on the equation of state as well on the elastic properties have been investigated. The calculations have shown that the hexagonal close packed structure in FeNi is more isotropic than the face-centered cubic structure, and that adding Mg to Fe has a large impact on the elastic properties.

Finally, the effects of disorder due to thermal motion of the atoms have been investigated through ab-initio molecular dynamics simulations. Within the limits of this method and the setup, it is found that the face-centered cubic structure of molybdenum can be dynamically stabilized at high temperature, leading to a metastable structure, on the average. The dynamical stabilization of face-centered cubic molybdenum also rendered it possible to accurately calculate the lattice stability relative to the body-centered cubic phase. Inclusion of temperature effects for the lattice stability using ab-initio molecular dynamics simulations resolves the disagreement between ab-initio calculations and thermochemical methods.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2010. 126 p.
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1299
Iron, Nickel, Magnesium, Manganese, Molybdenum, Zirconium, Elastic Constants, High pressure, Earth's core, Density-functional theory, Ab-initio, First-Principles, Core-level shifts, Molecular Dynamics, Phonons, Dynamical Instability
National Category
Condensed Matter Physics Other Physics Topics
urn:nbn:se:liu:diva-53584 (URN)978-91-7393-445-9 (ISBN)
Public defence
2010-03-12, Planck, Fysikhuset, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Available from: 2010-02-11 Created: 2010-01-25 Last updated: 2010-03-29Bibliographically approved

Open Access in DiVA

No full text

Search in DiVA

By author/editor
Asker, ChristianGrimvall, AndersAbrikosov, Igor
By organisation
Theoretical Physics The Institute of TechnologyStatistics

Search outside of DiVA

GoogleGoogle Scholar
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

Total: 74 hits
ReferencesLink to record
Permanent link

Direct link