Search for dissertations about: "Density Functional Theory"

Showing result 21 - 25 of 609 swedish dissertations containing the words Density Functional Theory.

  2. 21. Efficient Density-Functional-Based Calculational Methods for Surfaces

    Author : Lennart Bengtsson; Chalmers tekniska högskola; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; potential energy surfaces; pseudopotentials; surface physics; density functional theory; optimization techniques; computer simulations;

    Abstract : During the last decades, computer simulations have become an important tool for the study of elementary surface processes, such as atomic and molecular adsorption, diffusion of ad-atoms and surface recombination. The knowledge gained by such studies can be used to understand and develop technologically important processes such as catalysis and crystal growth. READ MORE

  4. 22. Foundation of Density Functionals in the Presence of Magnetic Field

    Author : Andre Laestadius; Michael Benedicks; Trygve Helgaker; KTH; []
    Keywords : 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;

    Abstract : 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. READ MORE

  5. 23. Interfacial properties of calcium montmorillonite in aqueous solutions : Density functional theory and classical molecular dynamics studies on the electric double layer

    Author : Guomin Yang; Göran Lindbergh; Ivars Neretnieks; Michael Holmboe; Jan Forsman; KTH; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Clay minerals; Bentonite; density functional theory; molecular dynamics; GROMACS; electric double layer; electrolytes; ionic liquids; primitive model; CLAYFF forcefield.; Chemical Engineering; Kemiteknik;

    Abstract : The swelling properties of Bentonite are highly affected by clay content and the clay-water interactions that arise from the ion distribution in the diffuse double layer formed near the charged montmorillonite (or smectite) surfaces. Existing continuum models describing the electric double layers, such as classical Poisson-Boltzmann and DLVO theory, ignore the ion-ion correlations, which are especially important for multivalent ions at high surface charge and ionic strength. READ MORE

  6. 24. Vibrational and Structural Characterisation in Two Perovskite Challenges: A Density Functional Theory Study

    Author : Erik Jedvik Granhed; Chalmers tekniska högskola; []
    Keywords : 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;

    Abstract : 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. READ MORE

  7. 25. Nonparametric Functional Estimation under Order Restrictions

    Author : Dragi Anevski; Matematisk statistik; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; monotonicity; convexity; deconvolution; kernel smoothing; NPMLE; long range dependence; greatest convex minorant; mixing; Density estimation; limit distribution.; regression; Mathematics; Matematik;

    Abstract : This thesis consists of three papers (Papers A-C) on problems in nonparametric functional estimation, in particular density and regression function estimation and deconvolution, under order assumptions. Pointwise limit distribution results are stated for the obtained estimators, which include isotonic regression estimates, nonparametric maximum likelihood estimates of monotone densities, estimates of convex regression and density functions and deconvolution estimates. READ MORE