Sökning: "klassisk mekanik"

Visar resultat 16 - 20 av 45 avhandlingar innehållade orden klassisk mekanik.

1. 16. Model Vertices Beyond the GW Approximation

   Författare :Mikael Hindgren; Matematisk fysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Matematisk och allmän teoretisk fysik; thermodynamics; statistical physics; gravitation; GW approximation; Electron self energy; Green s function; consistency; local-field corrections; vertex function; conserving approximations; variational energies; Mathematical and general theoretical physics; classical mechanics; relativity; quantum mechanics; klassisk mekanik; kvantmekanik; relativitet; statistisk fysik; termodynamik; Fysicumarkivet A:1997:Hindgren;

   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

3. 17. Self-consistency and the GW-approximation

   Författare :Bengt Holm; Matematisk fysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Matematisk och allmän teoretisk fysik; thermodynamics; Spectral Function; Greens functions; Self-energy; classical mechanics; Mathematical and general theoretical physics; Quasiparticle.; quantum mechanics; relativity; statistical physics; gravitation; klassisk mekanik; kvantmekanik; relativitet; statistisk fysik; termodynamik; Fysicumarkivet A:1997:Holm;

   Sammanfattning : The effects of self-consistency in the GW-approximation are studied. The $GWA$ is known to describe the electronic properties of a wide range of materials very well. However, the calculations made so far have not taken into account the issue of self-consistency, which is implied in the original formulation of the $GWA$. LÄS MER

4. 18. Rotational Bands and Pairing Interaction in the Shell Model

   Författare :Andrius Juodagalvis; Matematisk fysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; statistical physics; gravitation; relativity; Rotational bands; Shell model; Cranked Nilsson-Strutinsky; Pairing interaction; Backbending; Band termination; Proton-neutron pairing; Quadrupole electromagnetic moments and transition strengths; N=Z nuclei; Mathematical and general theoretical physics; quantum mechanics; classical mechanics; klassisk mekanik; Matematisk och allmän teoretisk fysik; thermodynamics; Fysicumarkivet A:2000:Juodagalvis; termodynamik; statistisk fysik; kvantmekanik; relativitet;

   Sammanfattning : One of the goals pursued in the present research was to understand the nuclear phenomena (such as rotational bands, their backbending and termination, deformation, pairing correlations, etc.) using different views provided by different nuclear models. LÄS MER

5. 19. Variational Methods in Combinatorial Optimization and Phylogeny Reconstruction

   Författare :Henrik Jönsson; Beräkningsbiologi och biologisk fysik - Genomgår omorganisation; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; statistical physics; gravitation; relativity; annealing; variational; mean-field; phylogeny; constraint satisfaction; combinatorial optimization; maximum likelihood; Physics; Fysik; Mathematical and general theoretical physics; quantum mechanics; classical mechanics; klassisk mekanik; kvantmekanik; relativitet; statistisk fysik; termodynamik; Fysicumarkivet A:2001:Jönsson; Matematisk och allmän teoretisk fysik; thermodynamics;

   Sammanfattning : Algorithms based on the variational approach, as used in statistical physics, are developed. For constraint satisfaction problems a novel cost function, based on information-theoretic arguments, is introduced, and an algorithm similar to the mean-field annealing algorithm is proposed. LÄS MER

7. 20. Necked-in Superdeformed Nuclei

   Författare :Lars-Ove Jönsson; Matematisk fysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Matematisk och allmän teoretisk fysik; thermodynamics; statistical physics; gravitation; cranked Nilsson-Strutinsky; superdeformation; necked-in shapes; RPA; giant dipole resonance; finite-range liquid drop model; Mathematical and general theoretical physics; classical mechanics; relativity; quantum mechanics; klassisk mekanik; kvantmekanik; relativitet; statistisk fysik; termodynamik; Fysicumarkivet A:1997:Jönsson;

   Sammanfattning : Superdeformation, i.e. elongated shapes with the longest axis approximately twice as long as the shorter axes, has provided many new insights in nuclear structure. In this dissertation the possibility of forming superdeformed states related to two connected spheres, having a more or less pronounced neck, is investigated. LÄS MER