{"id":{"repo_id":"heid-diss","oai_identifier":"oai:archiv.ub.uni-heidelberg.de:2105"},"canonical_url":"https://search.dev.ndltd.org/etd/heid-diss/oai:archiv.ub.uni-heidelberg.de:2105","repository":{"repo_id":"heid-diss","name":"Universität Heidelberg","base_url":"http://archiv.ub.uni-heidelberg.de/volltextserver/cgi/oai2"},"display":{"title":"Hamiltonian Flow Equations and the Electron-Phonon-Problem","abstract":"In this thesis we investigate the electron-phonon-system using the method of Flow Equations for Hamiltonians. In this continuous diagonalisation process the one particle energies and interaction constants are subject to a series of transformations, the ``flow'' of the Hamiltonian. They depend on a flow parameter l varying from zero to infinity. We give a proof that the asymptotic behaviour of the flow of the one-particle energies for large l is given by a constnat over squareroot of l behaviour. The constant may contain terms logarithmic in l and depends on electronic momentum k. This result is used to show that the transformation does lead to a blockdiagonal Hamiltonian decoupling the electron and the phonon subsystems. We obtain the same renormalization of the phonon energies as Wegner and Lenz, who neglected the shift of the electronic one-particle energies. The dependency of the renormalization of the electronic energies on the distance to the fermi surface is calculated. We investigate the transformation of the electronic one-particle operators. In the appendix we present a rigorous proof of the asymptotic behaviour. The l-dependency is changed by including an additional logarithmic factor and this refined asymptotic behaviour is investigated.","abstract_html":"In this thesis we investigate the electron-phonon-system using the method of Flow Equations for Hamiltonians. In this continuous diagonalisation process the one particle energies and interaction constants are subject to a series of transformations, the ``flow'' of the Hamiltonian. They depend on a flow parameter l varying from zero to infinity. We give a proof that the asymptotic behaviour of the flow of the one-particle energies for large l is given by a constnat over squareroot of l behaviour. The constant may contain terms logarithmic in l and depends on electronic momentum k. This result is used to show that the transformation does lead to a blockdiagonal Hamiltonian decoupling the electron and the phonon subsystems. We obtain the same renormalization of the phonon energies as Wegner and Lenz, who neglected the shift of the electronic one-particle energies. The dependency of the renormalization of the electronic energies on the distance to the fermi surface is calculated. We investigate the transformation of the electronic one-particle operators. In the appendix we present a rigorous proof of the asymptotic behaviour. The l-dependency is changed by including an additional logarithmic factor and this refined asymptotic behaviour is investigated.","abstract_has_math":false,"creators":["Schütte, Albrecht"],"institution":"Universität Heidelberg","degree_name":null,"degree_level":"thesis.doctoral","degree_discipline":null,"degree_department":null,"school":null,"contributors":["Wegner, Franz"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2002,"date_issued":"2002-04-17","date_published":"2002-04-17","updated_at":"2026-07-24T02:29:18Z","subjects":[],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://www.ub.uni-heidelberg.de/archiv/2105","outbound_label":"Repository record","outbound_source":"source_url"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Wegner, Franz"]},{"key":"dc:creator","label":"Author","values":["Schütte, Albrecht"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:publisher","label":"Institution","values":["Universitätsbibliothek Heidelberg"]},{"key":"dc:type","label":"Dc Type","values":["doctoralThesis"]},{"key":"thesis:degree_level","label":"Degree Level","values":["thesis.doctoral"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Universität Heidelberg"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["In this thesis we investigate the electron-phonon-system using the method of Flow Equations for Hamiltonians. In this continuous diagonalisation process the one particle energies and interaction constants are subject to a series of transformations, the ``flow'' of the Hamiltonian. They depend on a flow parameter l varying from zero to infinity. We give a proof that the asymptotic behaviour of the flow of the one-particle energies for large l is given by a constnat over squareroot of l behaviour. The constant may contain terms logarithmic in l and depends on electronic momentum k. This result is used to show that the transformation does lead to a blockdiagonal Hamiltonian decoupling the electron and the phonon subsystems. We obtain the same renormalization of the phonon energies as Wegner and Lenz, who neglected the shift of the electronic one-particle energies. The dependency of the renormalization of the electronic energies on the distance to the fermi surface is calculated. We investigate the transformation of the electronic one-particle operators. In the appendix we present a rigorous proof of the asymptotic behaviour. The l-dependency is changed by including an additional logarithmic factor and this refined asymptotic behaviour is investigated."]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Hamiltonian Flow Equations and the Electron-Phonon-Problem","Flussgleichungen für Hamiltonoperatoren und das Elektron-Phonon-Problem"]}]}],"canonical_facts":{"dc:contributor":["Wegner, Franz"],"dc:creator":["Schütte, Albrecht"],"dc:description.abstract":["In this thesis we investigate the electron-phonon-system using the method of Flow Equations for Hamiltonians. In this continuous diagonalisation process the one particle energies and interaction constants are subject to a series of transformations, the ``flow'' of the Hamiltonian. They depend on a flow parameter l varying from zero to infinity. We give a proof that the asymptotic behaviour of the flow of the one-particle energies for large l is given by a constnat over squareroot of l behaviour. The constant may contain terms logarithmic in l and depends on electronic momentum k. This result is used to show that the transformation does lead to a blockdiagonal Hamiltonian decoupling the electron and the phonon subsystems. We obtain the same renormalization of the phonon energies as Wegner and Lenz, who neglected the shift of the electronic one-particle energies. The dependency of the renormalization of the electronic energies on the distance to the fermi surface is calculated. We investigate the transformation of the electronic one-particle operators. In the appendix we present a rigorous proof of the asymptotic behaviour. The l-dependency is changed by including an additional logarithmic factor and this refined asymptotic behaviour is investigated."],"dc:format.medium":["application/pdf"],"dc:publisher":["Universitätsbibliothek Heidelberg"],"dc:title":["Hamiltonian Flow Equations and the Electron-Phonon-Problem","Flussgleichungen für Hamiltonoperatoren und das Elektron-Phonon-Problem"],"dc:type":["doctoralThesis"],"thesis:degree_level":["thesis.doctoral"],"thesis:institution_name":["Universität Heidelberg"]},"updated_at":"2026-07-24T02:29:18Z"}