Sökning: "density functional analysis"

Visar resultat 1 - 5 av 151 avhandlingar innehållade orden density functional analysis.

1. 1. Foundation of Density Functionals in the Presence of Magnetic Field

   Författare :Andre Laestadius; Michael Benedicks; Trygve Helgaker; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Current density functional theory; Hohenberg-Kohn theorems; paramagnetic current density functionals; Kohn-Sham theory; Levy-Lieb functional; variational principle; N-representable; degeneracy; Mathematics; Matematik;

   Sammanfattning : This thesis contains four articles related to mathematical aspects of Density Functional Theory.In Paper A, the theoretical justification of density methods formulated with current densities is addressed. It is shown that the set of ground-states is determined by the ensemble-representable particle and paramagnetic current density. LÄS MER

3. 2. Atomistic modelling of functional solid oxides for industrial applications : Density Functional Theory, hybrid functional and GW-based studies

   Författare :Cecilia Århammar; Rajeev Ahuja; Steven Louie; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; density functional theory; oxides; GW; Condensed matter physics; Kondenserade materiens fysik; Magnetism; Magnetism; Defects and diffusion; Defekter och diffusion;

   Sammanfattning : In this Thesis a set of functional solid oxides for industrial applications have been addressed by first principles and thermodynamical modelling. More specificially, measurable quantities such as Gibbs free energy, geometry and electronic structure have been calculated and compared when possible with experimental data. LÄS MER

4. 3. Density Functional Theory in Computational Materials Science

   Författare :Jorge Mario Osorio Guillén; Rajeev Ahuja; Börje Johansson; Bruce N. Harmon; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; Density Functional Theory; High Pressure; Phase Transitions; Elastic Properties; Lithium Batteries; Dilute Magnetic Semiconductors; Fysik; Physics; Fysik;

   Sammanfattning : The present thesis is concerned to the application of first-principles self-consistent total-energy calculations within the density functional theory on different topics in materials science. Crystallographic phase-transitions under high-pressure has been study for TiO2, FeI2, Fe3O4, Ti, the heavy alkali metals Cs and Rb, and C3N4. LÄS MER

5. 4. Vibrational and Structural Characterisation in Two Perovskite Challenges: A Density Functional Theory Study

   Författare :Erik Jedvik Granhed; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; phonon; chemical expansion; materials modelling; oxyhydride; polaron; vibrational analysis; BaTiO3; BaZrO3; anti-ferrodistortive; density functional theory;

   Sammanfattning : The modelling of perovskites using density functional theory (DFT) can sometimes be a challenge with many different states very close in energy. In particular, the tilting of the inscribed octahedron, as well as the formation of electron polarons, leads to states with energy differences in the meV range. LÄS MER

7. 5. Transition metal and alloy catalysts in the light of computational materials modelling

   Författare :Ageo Meier de Andrade; Peter Broqvist; Jolla Kullgren; Elsebeth Schröder; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; density functional theory; dispersion corrections; density functional analysis; transition metal; alloys; work function; lignin valorization; keto-enol tautomerization; Kemi med inriktning mot materialkemi; Chemistry with specialization in Materials Chemistry;

   Sammanfattning : This thesis is built around two pillars. One is heterogeneous catalysis in the broader context of green chemistry. The focus here is on identifying catalytically active materials suitable for the valorization of renewable feedstocks. LÄS MER