Anharmonic contributions to ab initio computed thermodynamic material properties / Albert Glensk ; Gutachter Prof. Dr. rer. nat. Wolf Gero Schmidt, Gutachter Prof Dr. rer. nat. Jörg Neugebauer, Gutachter Prof. Dr. Michael Finnis. Paderborn, 2016
Inhalt
- Acknowledgements
- Abstract
- Contents
- 1 Introduction: Ab initio thermodynamics
- 2 Theory
- 2.1 Entropic quantities and their relation to ensemble averages from molecular dynamics
- 2.2 From the many-body problem to density functional theory
- 2.3 Approximate theories of lattice vibrations
- 2.3.1 Independent harmonic oscillators — The Einstein crystal
- 2.3.2 Debye and Grüneisen Approximation
- 2.3.3 Harmonic and Quasiharmonic Approximation
- 2.3.4 Methods beyond the quasiharmonic approximation
- 2.4 Solving lattice vibrations numerically exactly
- 3 Methodological developments
- 3.1 Efficient sampling of anharmonic contributions in bulk systems
- 3.1.1 Analysis of harmonic lattice dynamics at high temperatures
- 3.1.2 Local Anharmonic (LA) approximation
- 3.1.3 Comparison of reference potentials
- 3.2 Fully ab initio description of point defects at high temperatures
- 4 Results: Impact of anharmonicity on the thermodynamics of selected material systems
- 4.1 Fcc elements: A wide range study
- 4.1.1 Anharmonic free energy contributions in LDA and GGA
- 4.1.2 Effects on derived quantities: Heat Capacity, Expansion
- 4.2 Beyond standard DFT: RPA up to melting
- 4.3 Binary systems: From Mg and Si to Mg2Si
- 4.4 Point Defects
- 5 Summary and Outlook
- A Supplement
- A.1 Rewriting the quasiharmonic total energy
- A.2 Local Anharmonic approximation
- A.3 Details of calculations on bulk systems
- Bibliography
- List of Publications