Change search
ReferencesLink to record
Permanent link

Direct link
Mechanism of the body-centered cubic iron stabilization under the Earth core conditions
KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
Dalian University of Technology, China.
KTH, School of Engineering Sciences (SCI), Theoretical Physics, Condensed Matter Theory.
Show others and affiliations
(English)Manuscript (preprint) (Other academic)
National Category
Condensed Matter Physics
Identifiers
URN: urn:nbn:se:kth:diva-190123OAI: oai:DiVA.org:kth-190123DiVA: diva2:951617
Note

QC 20160810

Available from: 2016-08-09 Created: 2016-08-09 Last updated: 2016-08-16Bibliographically approved
In thesis
1. Developing semi-empirical ab initio based potentials in materials modeling
Open this publication in new window or tab >>Developing semi-empirical ab initio based potentials in materials modeling
2016 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Ab initiocalculation based on density function theory (DFT) is an accu-rate and efficient method for modelling material properties. It is performedby solving the Shrödinger equations with a few assumptions to obtain thephysical properties of the system. It is very computational demanding whendealing with large systems or long-time simulations. Developing empiricalpotentials on the basis ofab initiocalculations on smaller systems is a possi-ble way to solve this problem. The empirical potentials will benefit from theaccuracy ofab initiosimulations and can facilitate applications to large sys-tems and long-time simulations. In this thesis, we have performed two studiesregarding fitting empirical potentials: one is fitting an empirical Sutton-Chenpotential based onab initiosimulations for iron under extreme conditionsand the other one is fitting an improved Finnis-Sinclair potential for ternaryV-Ti-Cr alloy.In the first part, we focus on fitting a Sutton-Chen potential for solid Feunder the Earth’s inner core condition. Based onab initiomolecular dynam-ics (MD) simulation results, the Sutton-Chen potential is fitted to energies ofthe configurations obtained fromab initioMD simulations at the pressure of360 GPa and temperature of 6000 K. The method applied for the fitting isthe Particle Swarm Optimization (PSO) algorithm. The Sutton-Chen poten-tial can reproduce theab initioenergies with an error of 6.2 meV/atom. Setas the same withab initioMD simulations, classical MD using Sutton-Chenpotential can obtain the consistent results with those fromab initioMD sim-ulations at the pressure of 360 GPa and temperature of 6000 K. In order toexplore the size effect on the results, we extend the classical MD to large-sizesystems (from 1024 atoms to 65536 atoms). We also extend the temperaturerange to see the temperature effect on the results.In the second part, we develop an improved Finnis-Sinclair (IFS) potentialfor ternary V-Ti-Cr alloys. The interaction parameters of V-V, Ti-Ti andCr-Cr are fitted to the experimental lattice constants, cohesive energies andelastic constants. The binary alloy potential parameters are obtained byconstructing 3 binary alloy models (V15Ti, V15Cr, V8Ti8) and fitting to theirtheoretical lattice constants, cohesive energies and elastic constants. Finally,the IFS potential is successfully used to calculate mechanical properties andthe monovacancy formation energy in V-Ti-Cr alloy. It is also applied toinvestigate the composition effect on the mechanical properties of ternaryV-Ti-Cr alloys.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. x, 32 p.
Series
TRITA-FYS, ISSN 0280-316X
National Category
Condensed Matter Physics
Research subject
Physics
Identifiers
urn:nbn:se:kth:diva-190125 (URN)978-91-7729-056-8 (ISBN)
Presentation
2016-09-02, FE21, AlbaNova university center, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20160815

Available from: 2016-08-16 Created: 2016-08-09 Last updated: 2016-08-16Bibliographically approved

Open Access in DiVA

No full text

Search in DiVA

By author/editor
Belonoshko, AnatolyLukinov, TymofiyFu, Jie
By organisation
Condensed Matter Theory
Condensed Matter Physics

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: 77 hits
ReferencesLink to record
Permanent link

Direct link