Static and Dynamic Correlation Effects in Atoms
(2002) Abstract
 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.
The thesis has an introductory chapter with a brief discussion of the problem of describing electron correlation, in addition to an introduction to the concept of conserving approximations in manybody perturbation theory. The main part of the thesis consists of four research papers, whereof two consider atoms in strong laser pulses and two deal with ground state energy calculations.
Considering atoms in... (More)  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.
The thesis has an introductory chapter with a brief discussion of the problem of describing electron correlation, in addition to an introduction to the concept of conserving approximations in manybody perturbation theory. The main part of the thesis consists of four research papers, whereof two consider atoms in strong laser pulses and two deal with ground state energy calculations.
Considering atoms in strong laser pulses, the problem of including correlation effects is studied by employing a onedimensional model atom, which allows for an exact solution. While this model differs from the real atom, it is a convenient testing ground for studying the effects of electron correlation, since the characteristic features of the experimental results appear also here. The description is based on solving the timedependent Schr"odinger equation, exactly or using some simplified form of the twoparticle wave function.
The ground state energy of atoms is calculated using manybody perturbation theory. Due to computational difficulties, this theory has previously only to a small extent been employed in energy calculations. By using variational energy functionals, the computational effort reduces significantly, and total energies of atoms are obtained at different approximation levels. From these calculations, it has become clearer which physical mechanisms that must be included in total energy calculations. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/465099
 author
 Dahlen, NilsErik ^{LU}
 supervisor
 opponent

 Rex. W. Godby, Rex. W. Godby, Professor, The University of York
 organization
 publishing date
 2002
 type
 Thesis
 publication status
 published
 subject
 keywords
 magnetic and optical properties, electrical, Condensed matter:electronic structure, relaxation, magnetic resonance, supraconductors, spectroscopy, Kondenserade materiens egenskaper:elektronstruktur, Atom och molekylärfysik, Atomic and molecular physics, spektroskopi, magnetisk resonans, egenskaper (elektriska, supraledare, magnetiska och optiska), variational energies, double ionization, Electron correlation, laseratom interaction, Fysicumarkivet A:2002:Dahlen, conserving approximations, Green's functions, GWapproximation
 pages
 142 pages
 publisher
 Nils Erik Dahlen, Sölvegatan 14A, SE223 62 Lund, Sweden,
 defense location
 Fys F
 defense date
 20021105 10:15:00
 ISBN
 9162854046
 language
 English
 LU publication?
 yes
 additional info
 Article: 1. Nils Erik Dahlen and Robert van Leeuwen,"Double ionization of a twoelectron system inthe timedependent extended HartreeFockapproximation", printed in Physical Review A,Vol. 64, p023405 (2001). Article: 2. Nils Erik Dahlen, "Effect of electroncorrelation on the twoparticle dynamics of ahelium atom in a strong laser pulse",printed in International Journal of ModernPhysics B, Vol. 16, p415 (2002). Article: 3. Nils Erik Dahlen and Ulf von Barth,"Variational energy functionals tested on atoms",to be submitted to Physical Review B. Article: 4. Nils Erik Dahlen and Ulf von Barth,"Variational MP2 theory", to be submitted toThe Journal of Chemical Physics.
 id
 53e5e1965071486b8deedd48e05385e3 (old id 465099)
 date added to LUP
 20160404 10:44:57
 date last changed
 20181121 21:00:34
@phdthesis{53e5e1965071486b8deedd48e05385e3, abstract = {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.<br/><br> <br/><br> The thesis has an introductory chapter with a brief discussion of the problem of describing electron correlation, in addition to an introduction to the concept of conserving approximations in manybody perturbation theory. The main part of the thesis consists of four research papers, whereof two consider atoms in strong laser pulses and two deal with ground state energy calculations.<br/><br> <br/><br> Considering atoms in strong laser pulses, the problem of including correlation effects is studied by employing a onedimensional model atom, which allows for an exact solution. While this model differs from the real atom, it is a convenient testing ground for studying the effects of electron correlation, since the characteristic features of the experimental results appear also here. The description is based on solving the timedependent Schr"odinger equation, exactly or using some simplified form of the twoparticle wave function.<br/><br> <br/><br> The ground state energy of atoms is calculated using manybody perturbation theory. Due to computational difficulties, this theory has previously only to a small extent been employed in energy calculations. By using variational energy functionals, the computational effort reduces significantly, and total energies of atoms are obtained at different approximation levels. From these calculations, it has become clearer which physical mechanisms that must be included in total energy calculations.}, author = {Dahlen, NilsErik}, isbn = {9162854046}, language = {eng}, publisher = {Nils Erik Dahlen, Sölvegatan 14A, SE223 62 Lund, Sweden,}, school = {Lund University}, title = {Static and Dynamic Correlation Effects in Atoms}, year = {2002}, }