{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/124476"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/124476","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Path-integral simulations of solid and liquid atomic hydrogen","abstract":"Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2026-05-01","abstract_html":"Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2026-05-01","abstract_has_math":false,"creators":["Ly, Kevin Kim"],"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","Schleife, André","Lorenz, Virginia O","Gammie, Charles F"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2024,"date_issued":"2024-05","date_published":"2024-05","updated_at":"2026-07-22T22:25:00Z","subjects":["Quantum Monte Carlo","Atomic Hydrogen","Machine Learning","Lattice Dynamics"],"languages":["en","eng"],"rights":["Copyright 2024 Kevin Ly"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://hdl.handle.net/2142/124476","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Ceperley, David M","Schleife, André","Lorenz, Virginia O","Gammie, Charles F"]},{"key":"dc:creator","label":"Author","values":["Ly, Kevin Kim"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2024-05","2023-11-30"]},{"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":["Quantum Monte Carlo","Atomic Hydrogen","Machine Learning","Lattice Dynamics"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en","eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2024 Kevin Ly"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://hdl.handle.net/2142/124476"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2026-05-01","The student, Kevin Ly, accepted the attached license on 2023-11-24 at 17:40.","The student, Kevin Ly, submitted this Dissertation for approval on 2023-11-24 at 17:46.","This Dissertation was approved for publication on 2023-11-30 at 16:13.","DSpace SAF Submission Ingestion Package generated from Vireo submission #20001 on 2024-09-16 at 00:41:52","For decades, the characterization of bulk hydrogen and its phases has challenged experimentalists and theorists alike. Solid atomic hydrogen, which requires extremely high pressures and has yet to be produced in the lab, seems just within reach. Accurate calculations of the solid phase are necessary to inform the next generation of experiments. For the theorist, hydrogen’s unique and erratic behavior requires novel and powerful techniques in simulation. We calculated the phonons of solid atomic hydrogen with reptation quantum Monte Carlo (RQMC). This is the first phonon calculation of this kind, made possible with a simple trick that we devised. We also simulated the lattice dynamics of LaH10, an analogue of solid atomic hydrogen which displays high- temperature superconductivity, with path-integral molecular dynamics. The resolution of our simulations allowed us to identify an intrinsic distortion of the superconducting structure which was previously thought to be extrinsic. Further investigation of this structural transformation also provided some insight into the design of hydrogen-rich superconductors. The improved resolution was enabled by the development of a machine-learned model that learned ab-initio calculations. Finally, we simulated the melting of solid atomic hydrogen. By combining RQMC and thermodynamic path-integral Monte Carlo, we believe that our results are the most accurate to date. Once again, these simulations were made possible by a machine-learned model. We found the melting line to be higher than previously suggested, though still below the projected superconducting temperature. We also found a clear decrease in the melting line with increasing pressure, reviving hopes that the liquid may be stable down to very low temperatures."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Path-integral simulations of solid and liquid atomic hydrogen"]}]}],"canonical_facts":{"dc:contributor":["Ceperley, David M","Schleife, André","Lorenz, Virginia O","Gammie, Charles F"],"dc:creator":["Ly, Kevin Kim"],"dc:date":["2024-05","2023-11-30"],"dc:description":["Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2026-05-01","The student, Kevin Ly, accepted the attached license on 2023-11-24 at 17:40.","The student, Kevin Ly, submitted this Dissertation for approval on 2023-11-24 at 17:46.","This Dissertation was approved for publication on 2023-11-30 at 16:13.","DSpace SAF Submission Ingestion Package generated from Vireo submission #20001 on 2024-09-16 at 00:41:52","For decades, the characterization of bulk hydrogen and its phases has challenged experimentalists and theorists alike. Solid atomic hydrogen, which requires extremely high pressures and has yet to be produced in the lab, seems just within reach. Accurate calculations of the solid phase are necessary to inform the next generation of experiments. For the theorist, hydrogen’s unique and erratic behavior requires novel and powerful techniques in simulation. We calculated the phonons of solid atomic hydrogen with reptation quantum Monte Carlo (RQMC). This is the first phonon calculation of this kind, made possible with a simple trick that we devised. We also simulated the lattice dynamics of LaH10, an analogue of solid atomic hydrogen which displays high- temperature superconductivity, with path-integral molecular dynamics. The resolution of our simulations allowed us to identify an intrinsic distortion of the superconducting structure which was previously thought to be extrinsic. Further investigation of this structural transformation also provided some insight into the design of hydrogen-rich superconductors. The improved resolution was enabled by the development of a machine-learned model that learned ab-initio calculations. Finally, we simulated the melting of solid atomic hydrogen. By combining RQMC and thermodynamic path-integral Monte Carlo, we believe that our results are the most accurate to date. Once again, these simulations were made possible by a machine-learned model. We found the melting line to be higher than previously suggested, though still below the projected superconducting temperature. We also found a clear decrease in the melting line with increasing pressure, reviving hopes that the liquid may be stable down to very low temperatures."],"dc:format":["application/pdf"],"dc:identifier":["https://hdl.handle.net/2142/124476"],"dc:language":["en","eng"],"dc:rights":["Copyright 2024 Kevin Ly"],"dc:subject":["Quantum Monte Carlo","Atomic Hydrogen","Machine Learning","Lattice Dynamics"],"dc:title":["Path-integral simulations of solid and liquid atomic hydrogen"],"dc:type":["text"],"thesis:degree_discipline":["Physics"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:00Z"}