{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/93047"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/93047","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Energy landscape statistics and coarsening in liquids: a relaxation mode analysis","abstract":"Energy landscape, the high dimensional energy surface in the configuration space, has been widely applied to interpret slow processes that occur over a long time scale, such as slow relaxations of supercooled liquids approaching the glass transition. Despite extensive simulation studies, experimental characterization of the energy landscape still remains a challenge. To address this challenge, in this work, we developed a relaxation mode analysis (RMA) for liquids under a framework analogous to the normal mode analysis for solids. Using RMA, complicated relaxations of liquids are decoupled into a distribution of relaxation modes, from which important statistics of relaxation times and activation barriers on the energy landscape become accessible from experimentally measurable two-point density-density correlation functions, e.g. using quasi-elastic and inelastic scattering experiments. As demonstrations, this RMA approach was used to analyze three empirical models, i.e. exponential relaxation, stretched exponential relaxation, and relaxation arising from normally distributed activation energies. Furthermore, we applied RMA to study the relaxations of a Kob-Andersen liquid when dynamical cooperativity emerges in the landscape-influenced regime using molecular dynamics simulations. The results revealed a prominent dynamic decoupling and a coarsening effect of the energy landscape at different length scales. These demonstrations suggest that RMA is a promising tool to extract energy landscape statistics from experimental data. In the end, we discuss the future extensions of RMA from both application and theoretical perspectives.","abstract_html":"Energy landscape, the high dimensional energy surface in the configuration space, has been widely applied to interpret slow processes that occur over a long time scale, such as slow relaxations of supercooled liquids approaching the glass transition. Despite extensive simulation studies, experimental characterization of the energy landscape still remains a challenge. To address this challenge, in this work, we developed a relaxation mode analysis (RMA) for liquids under a framework analogous to the normal mode analysis for solids. Using RMA, complicated relaxations of liquids are decoupled into a distribution of relaxation modes, from which important statistics of relaxation times and activation barriers on the energy landscape become accessible from experimentally measurable two-point density-density correlation functions, e.g. using quasi-elastic and inelastic scattering experiments. As demonstrations, this RMA approach was used to analyze three empirical models, i.e. exponential relaxation, stretched exponential relaxation, and relaxation arising from normally distributed activation energies. Furthermore, we applied RMA to study the relaxations of a Kob-Andersen liquid when dynamical cooperativity emerges in the landscape-influenced regime using molecular dynamics simulations. The results revealed a prominent dynamic decoupling and a coarsening effect of the energy landscape at different length scales. These demonstrations suggest that RMA is a promising tool to extract energy landscape statistics from experimental data. In the end, we discuss the future extensions of RMA from both application and theoretical perspectives.","abstract_has_math":false,"creators":["Cai, Zhikun"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Nuclear, Plasma, Radiolgc Engr","degree_department":null,"school":null,"contributors":["Zhang, Yang","Uddin, Rizwan"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2016,"date_issued":"2016-11-10T18:42:52Z","date_published":"2016-11-10T18:42:52Z","updated_at":"2026-07-22T22:26:35Z","subjects":["relaxation mode analysis","energy landscape","liquids","relaxation mode distribution","activation energy distribution"],"languages":["en"],"rights":["Copyright 2016 Zhikun Cai"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/93047","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Zhang, Yang","Uddin, Rizwan"]},{"key":"dc:creator","label":"Author","values":["Cai, Zhikun"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2016-11-10T18:42:52Z","2018-11-11T10:15:40Z","2016-07-12","2016-08"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Nuclear, Plasma, Radiolgc Engr"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"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":["relaxation mode analysis","energy landscape","liquids","relaxation mode distribution","activation energy distribution"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2016 Zhikun Cai"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/93047"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Energy landscape, the high dimensional energy surface in the configuration space, has been widely applied to interpret slow processes that occur over a long time scale, such as slow relaxations of supercooled liquids approaching the glass transition. Despite extensive simulation studies, experimental characterization of the energy landscape still remains a challenge. To address this challenge, in this work, we developed a relaxation mode analysis (RMA) for liquids under a framework analogous to the normal mode analysis for solids. Using RMA, complicated relaxations of liquids are decoupled into a distribution of relaxation modes, from which important statistics of relaxation times and activation barriers on the energy landscape become accessible from experimentally measurable two-point density-density correlation functions, e.g. using quasi-elastic and inelastic scattering experiments. As demonstrations, this RMA approach was used to analyze three empirical models, i.e. exponential relaxation, stretched exponential relaxation, and relaxation arising from normally distributed activation energies. Furthermore, we applied RMA to study the relaxations of a Kob-Andersen liquid when dynamical cooperativity emerges in the landscape-influenced regime using molecular dynamics simulations. The results revealed a prominent dynamic decoupling and a coarsening effect of the energy landscape at different length scales. These demonstrations suggest that RMA is a promising tool to extract energy landscape statistics from experimental data. In the end, we discuss the future extensions of RMA from both application and theoretical perspectives.","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2018-08-01","The student, Zhikun Cai, accepted the attached license on 2016-07-08 at 17:53.","The student, Zhikun Cai, submitted this Thesis for approval on 2016-07-08 at 17:54.","This Thesis was approved for publication on 2016-07-12 at 15:42.","DSpace SAF Submission Ingestion Package generated from Vireo submission #9838 on 2016-11-10 at 12:25:04","Made available in DSpace on 2016-11-10T18:42:52Z (GMT). No. of bitstreams: 2 CAI-THESIS-2016.pdf: 5864838 bytes, checksum: 1e9a27ea51f3e982cca9f7e6ea9b7391 (MD5) LICENSE.txt: 4207 bytes, checksum: 05a30b6172559d603ef2d101d1f75282 (MD5) Previous issue date: 2016-07-12","Embargo set by: Seth Robbins for item 95470 Lift date: 2018-11-10T18:43:22Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","U of I Only Restriction Lifted for Item 95470 on 2018-11-11T10:15:40Z."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Energy landscape statistics and coarsening in liquids: a relaxation mode analysis"]}]}],"canonical_facts":{"dc:contributor":["Zhang, Yang","Uddin, Rizwan"],"dc:creator":["Cai, Zhikun"],"dc:date":["2016-11-10T18:42:52Z","2018-11-11T10:15:40Z","2016-07-12","2016-08"],"dc:description":["Energy landscape, the high dimensional energy surface in the configuration space, has been widely applied to interpret slow processes that occur over a long time scale, such as slow relaxations of supercooled liquids approaching the glass transition. Despite extensive simulation studies, experimental characterization of the energy landscape still remains a challenge. To address this challenge, in this work, we developed a relaxation mode analysis (RMA) for liquids under a framework analogous to the normal mode analysis for solids. Using RMA, complicated relaxations of liquids are decoupled into a distribution of relaxation modes, from which important statistics of relaxation times and activation barriers on the energy landscape become accessible from experimentally measurable two-point density-density correlation functions, e.g. using quasi-elastic and inelastic scattering experiments. As demonstrations, this RMA approach was used to analyze three empirical models, i.e. exponential relaxation, stretched exponential relaxation, and relaxation arising from normally distributed activation energies. Furthermore, we applied RMA to study the relaxations of a Kob-Andersen liquid when dynamical cooperativity emerges in the landscape-influenced regime using molecular dynamics simulations. The results revealed a prominent dynamic decoupling and a coarsening effect of the energy landscape at different length scales. These demonstrations suggest that RMA is a promising tool to extract energy landscape statistics from experimental data. In the end, we discuss the future extensions of RMA from both application and theoretical perspectives.","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2018-08-01","The student, Zhikun Cai, accepted the attached license on 2016-07-08 at 17:53.","The student, Zhikun Cai, submitted this Thesis for approval on 2016-07-08 at 17:54.","This Thesis was approved for publication on 2016-07-12 at 15:42.","DSpace SAF Submission Ingestion Package generated from Vireo submission #9838 on 2016-11-10 at 12:25:04","Made available in DSpace on 2016-11-10T18:42:52Z (GMT). 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