Sökning: "variational energies"
Hittade 5 avhandlingar innehållade orden variational energies.
1. Model Vertices Beyond the GW Approximation
Sammanfattning : We study the effects of local vertex corrections to the self energy of the electron gas. We find that a vertex derived from time-dependent density-functional theory can give accurate self energies without including the explicit time dependence of the exchange-correlation potential provided, however, that a proper decay at large momentum transfer (large q) is built into the vertex function. LÄS MER
2. Static and Dynamic Correlation Effects in Atoms
Sammanfattning : The thesis considers the effects of electron correlation by studying the two opposite limits of atoms in the ground state and atoms in strong laser pulses. Computational methods and theoretical approaches differ significantly due to the different physical processes that are studied in these two cases. LÄS MER
3. Resonant states in modulation-doped heterostructures
Sammanfattning : This thesis deals with the properties of donors placed inside or outside a heterostructure quantum well (QW). The focus of the investigation has been on the formation of resonant states, which are a hybridization of the discrete localized impurity levels and the continuous two-dimensional QW subbands. LÄS MER
4. Thermodynamic Studies of Macromolecular Models
Sammanfattning : The thermodynamic properties of single chain polyelectrolyte and protein models are studied using Monte Carlo simulations and (for the polyelectrolyte models) variational calculations and high- and low-temperature expansions. A variational method is used for minimizing Lennard-Jones energies and for estimating end-to-end distances for a rigid Coulomb chain at finite temperatures. LÄS MER
5. Global Optimization in Computer Vision: Convexity, Cuts and Approximation Algorithms
Sammanfattning : Computer vision is today a wide research area including topics like robot vision, image analysis, pattern recognition, medical imaging and geometric reconstruction problems. Over the past decades there has been a rapid development in understanding and modeling different computer vision applications. LÄS MER
