Sökning: "local density approximation"
Visar resultat 1 - 5 av 59 avhandlingar innehållade orden local density approximation.
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. van der Waals Density Functionals
Sammanfattning : Methods using local or semi local approximations (LDA, GGA etc.) for the exchange-correlation energy in the density-functional theory (DFT) do not include van der Waals interactions. LÄS MER
3. Structure and energetics of kappa alumina (-Al2O3) calculated from first principles
Sammanfattning : .... LÄS MER
4. Nonlocal Correlations in Density Functional Theory
Sammanfattning : In Density Functional Theory, the widely used local and semilocal approximations to the exchange-correlation energy, the local density approximation (LDA) and the generalized gradient approximations (GGAs), lack a physical description of truly nonlocal correlation effects, which are absolutely essential for a proper description of soft matter. A scheme is proposed that provides a basis for systematic improvements beyond LDA and GGA, including correlations at intermediate and long range, giving rise to bonds of pure van der Waals type as well as more intricate, intermediate-range correlation bonds. LÄS MER
5. Van der Waals Interactions in Density Functional Theory
Sammanfattning : Density functional theory is a very important method for calculating ground-state properties for atoms, molecules and solids. Albeit exact in principle, its implementation requires an approximation for the so-called exchange-correlation energy. LÄS MER