{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/20316"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/20316","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Path integral Monte Carlo simulations of solid H2 surfaces and thin 4He films on H2 substrates","abstract":"Based on Richard P. Feynman's formulation of quantum mechanics, Path Integral Monte Carlo is a computational ab-initio method to calculate finite temperature equilibrium properties of quantum many-body systems. As input, only fundamental physical constants and pair-potentials are required. We carry out the first ab-initio particle simulations of three related physical systems. First, the bare H$\\sb2$ substrate is simulated between 0.5 and 1.3K, because a liquid H$\\sb2$ film is a candidate for a new superfluid. We find evidence of quantum exchange in surface terraces for up to 1K. Second, the melting of the H$\\sb2$ surface between 3 and 15K is examined since this is the cleanest example of quantum surface melting. Third, atomically thin superfluid $\\sp4$He films on H$\\sb2$ surfaces are simulated, calculating binding energies per $\\sp4$He atom and third sound, an important experimental probe for superfuid $\\sp4$He films. For all systems we compute density profiles perpendicular and parallel to the surface and compare to experiment. We treat both H$\\sb2$ molecules and $\\sp4$He atoms on the same footing, as spherical particles. For simulations of bulk/vapor interfaces and surface adsorption, a realistic representation of the macroscopic surface is crucial. Therefore, we introduce an external potential to account for arbitrarily layered substrates and long-range corrections. Two algorithms for parallel computers with independent processors are introduced, one to manage concurrent simulations of entire phase-diagrams, and one to improve input/output speed for files shared by all processors.","abstract_html":"Based on Richard P. Feynman's formulation of quantum mechanics, Path Integral Monte Carlo is a computational ab-initio method to calculate finite temperature equilibrium properties of quantum many-body systems. As input, only fundamental physical constants and pair-potentials are required. We carry out the first ab-initio particle simulations of three related physical systems. First, the bare H$\\sb2$ substrate is simulated between 0.5 and 1.3K, because a liquid H$\\sb2$ film is a candidate for a new superfluid. We find evidence of quantum exchange in surface terraces for up to 1K. Second, the melting of the H$\\sb2$ surface between 3 and 15K is examined since this is the cleanest example of quantum surface melting. Third, atomically thin superfluid $\\sp4$He films on H$\\sb2$ surfaces are simulated, calculating binding energies per $\\sp4$He atom and third sound, an important experimental probe for superfuid $\\sp4$He films. For all systems we compute density profiles perpendicular and parallel to the surface and compare to experiment. We treat both H$\\sb2$ molecules and $\\sp4$He atoms on the same footing, as spherical particles. For simulations of bulk/vapor interfaces and surface adsorption, a realistic representation of the macroscopic surface is crucial. Therefore, we introduce an external potential to account for arbitrarily layered substrates and long-range corrections. Two algorithms for parallel computers with independent processors are introduced, one to manage concurrent simulations of entire phase-diagrams, and one to improve input/output speed for files shared by all processors.","abstract_has_math":true,"creators":["Wagner, Marcus"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Physics","degree_department":null,"school":null,"contributors":["Ceperley, David M."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2011,"date_issued":"2011-05-07T12:35:46Z","date_published":"2011-05-07T12:35:46Z","updated_at":"2026-07-22T22:25:15Z","subjects":["Physics, Condensed Matter","Engineering, Materials Science","Computer Science"],"languages":["eng"],"rights":["Copyright 1994 Wagner, Marcus"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9512584","(UMI)AAI9512584"],"render_values":[{"text":"AAI9512584","href":null,"code":true},{"text":"(UMI)AAI9512584","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/20316","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Ceperley, David M."]},{"key":"dc:creator","label":"Author","values":["Wagner, Marcus"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2011-05-07T12:35:46Z","10000-01-01","1994"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Physics"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Physics, Condensed Matter","Engineering, Materials Science","Computer Science"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 1994 Wagner, Marcus"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9512584","(UMI)AAI9512584","http://hdl.handle.net/2142/20316"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Based on Richard P. Feynman's formulation of quantum mechanics, Path Integral Monte Carlo is a computational ab-initio method to calculate finite temperature equilibrium properties of quantum many-body systems. As input, only fundamental physical constants and pair-potentials are required. We carry out the first ab-initio particle simulations of three related physical systems. First, the bare H$\\sb2$ substrate is simulated between 0.5 and 1.3K, because a liquid H$\\sb2$ film is a candidate for a new superfluid. We find evidence of quantum exchange in surface terraces for up to 1K. Second, the melting of the H$\\sb2$ surface between 3 and 15K is examined since this is the cleanest example of quantum surface melting. Third, atomically thin superfluid $\\sp4$He films on H$\\sb2$ surfaces are simulated, calculating binding energies per $\\sp4$He atom and third sound, an important experimental probe for superfuid $\\sp4$He films. For all systems we compute density profiles perpendicular and parallel to the surface and compare to experiment. We treat both H$\\sb2$ molecules and $\\sp4$He atoms on the same footing, as spherical particles. For simulations of bulk/vapor interfaces and surface adsorption, a realistic representation of the macroscopic surface is crucial. Therefore, we introduce an external potential to account for arbitrarily layered substrates and long-range corrections. Two algorithms for parallel computers with independent processors are introduced, one to manage concurrent simulations of entire phase-diagrams, and one to improve input/output speed for files shared by all processors.","Made available in DSpace on 2011-05-07T12:35:46Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9512584.pdf: 8511974 bytes, checksum: 9ae05c5e82ff6fafa38c87593d81eeaa (MD5) Previous issue date: 1994","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:43:04Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:18:48-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission","ETDs are only available to UIUC Users without author permission","U of I Only"]},{"key":"dc:title","label":"Title","values":["Path integral Monte Carlo simulations of solid H2 surfaces and thin 4He films on H2 substrates","Path integral Monte Carlo simulations of solid molecular hydrogen surfaces and thin helium-4 films on molecular hydrogen substrates"]}]}],"canonical_facts":{"dc:contributor":["Ceperley, David M."],"dc:creator":["Wagner, Marcus"],"dc:date":["2011-05-07T12:35:46Z","10000-01-01","1994"],"dc:description":["Based on Richard P. Feynman's formulation of quantum mechanics, Path Integral Monte Carlo is a computational ab-initio method to calculate finite temperature equilibrium properties of quantum many-body systems. As input, only fundamental physical constants and pair-potentials are required. We carry out the first ab-initio particle simulations of three related physical systems. First, the bare H$\\sb2$ substrate is simulated between 0.5 and 1.3K, because a liquid H$\\sb2$ film is a candidate for a new superfluid. We find evidence of quantum exchange in surface terraces for up to 1K. Second, the melting of the H$\\sb2$ surface between 3 and 15K is examined since this is the cleanest example of quantum surface melting. Third, atomically thin superfluid $\\sp4$He films on H$\\sb2$ surfaces are simulated, calculating binding energies per $\\sp4$He atom and third sound, an important experimental probe for superfuid $\\sp4$He films. For all systems we compute density profiles perpendicular and parallel to the surface and compare to experiment. We treat both H$\\sb2$ molecules and $\\sp4$He atoms on the same footing, as spherical particles. For simulations of bulk/vapor interfaces and surface adsorption, a realistic representation of the macroscopic surface is crucial. Therefore, we introduce an external potential to account for arbitrarily layered substrates and long-range corrections. Two algorithms for parallel computers with independent processors are introduced, one to manage concurrent simulations of entire phase-diagrams, and one to improve input/output speed for files shared by all processors.","Made available in DSpace on 2011-05-07T12:35:46Z (GMT). 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