Sökning: "Density functional theory"
Visar resultat 21 - 25 av 611 avhandlingar innehållade orden Density functional theory.
21. Efficient Density-Functional-Based Calculational Methods for Surfaces
Sammanfattning : 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. LÄS MER
22. Foundation of Density Functionals in the Presence of Magnetic Field
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
23. Interfacial properties of calcium montmorillonite in aqueous solutions : Density functional theory and classical molecular dynamics studies on the electric double layer
Sammanfattning : 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. LÄS MER
24. Vibrational and Structural Characterisation in Two Perovskite Challenges: A Density Functional Theory Study
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
25. Nonparametric Functional Estimation under Order Restrictions
Sammanfattning : 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. LÄS MER