{"id":{"repo_id":"aachen","oai_identifier":"oai:publications.rwth-aachen.de:61448"},"canonical_url":"https://search.dev.ndltd.org/etd/aachen/oai:publications.rwth-aachen.de:61448","repository":{"repo_id":"aachen","name":"RWTH Aachen University","base_url":"https://publications.rwth-aachen.de/oai2d"},"display":{"title":"Kritische spezifische Wärme in begrenzten Systemen mit Dirichlet-Oberflächen","abstract":"The present work investigates the influence of real boundary conditions on the critical behaviour of confined system close to the temperature of a second order phase transition of the bulk. This is done analytically by applying the methods of the field theory of critical phenomena to a half-space geometry with a completely suppressed order parameter on the surface, the so-called Dirichlet boundary conditions. For the first time the surface specific heat is calculated to next to leading order in a fixed dimension both above and below the critical temperature. The results are compared with the data of recent experiments on Helium in plate geometry close to the lambda transition. Apart from the experimentally known bulk amplitudes no adaptable parameters are used. Above the critical temperature a semi-quantitative agreement of theory and experiment is found, whereas the experimental data cannot be explained below the lambda point. Possible reasons for this discrepancy are discussed. Secondly a new method to approximate Dirichlet boundary conditions in Monte Carlo simulations of lattice spin systems is presented. In comparison with established realizations both a better suppression of the order parameter on the boundary and the theoretically predicted scaling behaviour is achieved. Data generated with the new method shows agreement with theory within the expected errors.","abstract_html":"The present work investigates the influence of real boundary conditions on the critical behaviour of confined system close to the temperature of a second order phase transition of the bulk. This is done analytically by applying the methods of the field theory of critical phenomena to a half-space geometry with a completely suppressed order parameter on the surface, the so-called Dirichlet boundary conditions. For the first time the surface specific heat is calculated to next to leading order in a fixed dimension both above and below the critical temperature. The results are compared with the data of recent experiments on Helium in plate geometry close to the lambda transition. Apart from the experimentally known bulk amplitudes no adaptable parameters are used. Above the critical temperature a semi-quantitative agreement of theory and experiment is found, whereas the experimental data cannot be explained below the lambda point. Possible reasons for this discrepancy are discussed. Secondly a new method to approximate Dirichlet boundary conditions in Monte Carlo simulations of lattice spin systems is presented. In comparison with established realizations both a better suppression of the order parameter on the boundary and the theoretically predicted scaling behaviour is achieved. Data generated with the new method shows agreement with theory within the expected errors.","abstract_has_math":false,"creators":["Mohr, Ulf"],"institution":"Publikationsserver der RWTH Aachen University","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["Dohm, Volker"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2000,"date_issued":"2000","date_published":"2000","updated_at":"2026-07-30T19:43:10Z","subjects":["info:eu-repo/classification/ddc/530","Physik","Phasenumwandlung zweiter Ordnung","Kritischer Punkt","Spezifische Wärmekapazität","Dirichlet-Problem","Feldtheorie","Monte-Carlo-Simulation"],"languages":["ger"],"rights":["info:eu-repo/semantics/openAccess"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-123111%22"],"render_values":[{"text":"https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-123111%22","href":"https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-123111%22","code":true}]}]},"links":{"outbound_url":"https://publications.rwth-aachen.de/record/61448","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Dohm, Volker"]},{"key":"dc:creator","label":"Author","values":["Mohr, Ulf"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:coverage","label":"Dc Coverage","values":["DE"]},{"key":"dc:date","label":"Dc Date","values":["2000"]},{"key":"dc:publisher","label":"Institution","values":["Publikationsserver der RWTH Aachen University"]},{"key":"dc:relation","label":"Dc Relation","values":["info:eu-repo/semantics/altIdentifier/urn/urn:nbn:de:hbz:82-opus-1343"]},{"key":"dc:type","label":"Dc Type","values":["info:eu-repo/semantics/doctoralThesis","info:eu-repo/semantics/publishedVersion"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["info:eu-repo/classification/ddc/530","Physik","Phasenumwandlung zweiter Ordnung","Kritischer Punkt","Spezifische Wärmekapazität","Dirichlet-Problem","Feldtheorie","Monte-Carlo-Simulation"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["ger"]},{"key":"dc:rights","label":"Dc Rights","values":["info:eu-repo/semantics/openAccess"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://publications.rwth-aachen.de/record/61448","https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-123111%22"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The present work investigates the influence of real boundary conditions on the critical behaviour of confined system close to the temperature of a second order phase transition of the bulk. This is done analytically by applying the methods of the field theory of critical phenomena to a half-space geometry with a completely suppressed order parameter on the surface, the so-called Dirichlet boundary conditions. For the first time the surface specific heat is calculated to next to leading order in a fixed dimension both above and below the critical temperature. The results are compared with the data of recent experiments on Helium in plate geometry close to the lambda transition. Apart from the experimentally known bulk amplitudes no adaptable parameters are used. Above the critical temperature a semi-quantitative agreement of theory and experiment is found, whereas the experimental data cannot be explained below the lambda point. Possible reasons for this discrepancy are discussed. Secondly a new method to approximate Dirichlet boundary conditions in Monte Carlo simulations of lattice spin systems is presented. In comparison with established realizations both a better suppression of the order parameter on the boundary and the theoretically predicted scaling behaviour is achieved. Data generated with the new method shows agreement with theory within the expected errors."]},{"key":"dc:source","label":"Dc Source","values":["Aachen : Publikationsserver der RWTH Aachen University IV, 182 S. : graph. Darst. (2000). = Aachen, Techn. Hochsch., Diss., 2000"]},{"key":"dc:title","label":"Title","values":["Kritische spezifische Wärme in begrenzten Systemen mit Dirichlet-Oberflächen"]}]}],"canonical_facts":{"dc:contributor":["Dohm, Volker"],"dc:coverage":["DE"],"dc:creator":["Mohr, Ulf"],"dc:date":["2000"],"dc:description":["The present work investigates the influence of real boundary conditions on the critical behaviour of confined system close to the temperature of a second order phase transition of the bulk. This is done analytically by applying the methods of the field theory of critical phenomena to a half-space geometry with a completely suppressed order parameter on the surface, the so-called Dirichlet boundary conditions. For the first time the surface specific heat is calculated to next to leading order in a fixed dimension both above and below the critical temperature. The results are compared with the data of recent experiments on Helium in plate geometry close to the lambda transition. Apart from the experimentally known bulk amplitudes no adaptable parameters are used. Above the critical temperature a semi-quantitative agreement of theory and experiment is found, whereas the experimental data cannot be explained below the lambda point. Possible reasons for this discrepancy are discussed. Secondly a new method to approximate Dirichlet boundary conditions in Monte Carlo simulations of lattice spin systems is presented. In comparison with established realizations both a better suppression of the order parameter on the boundary and the theoretically predicted scaling behaviour is achieved. Data generated with the new method shows agreement with theory within the expected errors."],"dc:identifier":["https://publications.rwth-aachen.de/record/61448","https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-123111%22"],"dc:language":["ger"],"dc:publisher":["Publikationsserver der RWTH Aachen University"],"dc:relation":["info:eu-repo/semantics/altIdentifier/urn/urn:nbn:de:hbz:82-opus-1343"],"dc:rights":["info:eu-repo/semantics/openAccess"],"dc:source":["Aachen : Publikationsserver der RWTH Aachen University IV, 182 S. : graph. Darst. (2000). = Aachen, Techn. 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