{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/35910"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/35910","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Predicting Phase Equilibria Using COSMO-Based Thermodynamic Models and the VT-2004 Sigma-Profile","abstract":"Solvation-thermodynamics models based on computational quantum mechanics, such as the conductor-like screening model (COSMO), provide a good alternative to traditional group-contribution methods for predicting thermodynamic phase behavior. Two COSMO-based thermodynamic models are COSMO-RS (real solvents) and COSMO-SAC (segment activity coefficient). The main molecule-specific input for these models is the sigma profile, or the probability distribution of a molecular surface segment having a specific charge density. Generating the sigma profiles represents the most time-consuming and computationally expensive aspect of using COSMO-based methods. A growing number of scientists and engineers are interested in the COSMO-based thermodynamic models, but are intimidated by the complexity of generating the sigma profiles. This thesis presents the first free, open-literature database of 1,513 self-consistent sigma profiles, together with two validation examples. The offer of these profiles will enable interested scientists and engineers to use the quantum-mechanics-based, COSMO methods without having to do quantum mechanics. This thesis summarizes the application experiences reported up to October 2004 to guide the use of the COSMO-based methods. Finally, this thesis also provides a FORTRAN program and a procedure to generate additional sigma profiles consistent with those presented here, as well as a FORTRAN program to generate binary phase-equilibrium predictions using the COSMO-SAC model.","abstract_html":"Solvation-thermodynamics models based on computational quantum mechanics, such as the conductor-like screening model (COSMO), provide a good alternative to traditional group-contribution methods for predicting thermodynamic phase behavior. Two COSMO-based thermodynamic models are COSMO-RS (real solvents) and COSMO-SAC (segment activity coefficient). The main molecule-specific input for these models is the sigma profile, or the probability distribution of a molecular surface segment having a specific charge density. Generating the sigma profiles represents the most time-consuming and computationally expensive aspect of using COSMO-based methods. A growing number of scientists and engineers are interested in the COSMO-based thermodynamic models, but are intimidated by the complexity of generating the sigma profiles. This thesis presents the first free, open-literature database of 1,513 self-consistent sigma profiles, together with two validation examples. The offer of these profiles will enable interested scientists and engineers to use the quantum-mechanics-based, COSMO methods without having to do quantum mechanics. This thesis summarizes the application experiences reported up to October 2004 to guide the use of the COSMO-based methods. Finally, this thesis also provides a FORTRAN program and a procedure to generate additional sigma profiles consistent with those presented here, as well as a FORTRAN program to generate binary phase-equilibrium predictions using the COSMO-SAC model.","abstract_has_math":false,"creators":["Oldland, Richard Justin"],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Chemical Engineering","degree_department":"Chemical Engineering","school":null,"contributors":[],"advisors":[],"committee_chairs":["Liu, Y. A."],"committee_members":["Davis, Richey M.","Marand, Eva"],"year":2004,"date_issued":"2004-11-16","date_published":"2004-11-16","updated_at":"2026-07-22T22:19:16Z","subjects":["COSMO-RS","VT-2004","computational thermodynamics","COSMO-SAC","COSMO","solvation thermodynamics","sigma profile"],"languages":[],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-12022004-141526"],"render_values":[{"text":"etd-12022004-141526","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/35910","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Liu, Y. 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Two COSMO-based thermodynamic models are COSMO-RS (real solvents) and COSMO-SAC (segment activity coefficient). The main molecule-specific input for these models is the sigma profile, or the probability distribution of a molecular surface segment having a specific charge density. Generating the sigma profiles represents the most time-consuming and computationally expensive aspect of using COSMO-based methods. A growing number of scientists and engineers are interested in the COSMO-based thermodynamic models, but are intimidated by the complexity of generating the sigma profiles. This thesis presents the first free, open-literature database of 1,513 self-consistent sigma profiles, together with two validation examples. The offer of these profiles will enable interested scientists and engineers to use the quantum-mechanics-based, COSMO methods without having to do quantum mechanics. This thesis summarizes the application experiences reported up to October 2004 to guide the use of the COSMO-based methods. Finally, this thesis also provides a FORTRAN program and a procedure to generate additional sigma profiles consistent with those presented here, as well as a FORTRAN program to generate binary phase-equilibrium predictions using the COSMO-SAC model."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:title","label":"Title","values":["Predicting Phase Equilibria Using COSMO-Based Thermodynamic Models and the VT-2004 Sigma-Profile"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Liu, Y. A."],"dc:contributor.committeemember":["Davis, Richey M.","Marand, Eva"],"dc:contributor.department":["Chemical Engineering"],"dc:creator":["Oldland, Richard Justin"],"dc:date.accessioned":["2014-03-14T20:48:45Z"],"dc:date.available":["2014-03-14T20:48:45Z","2004-12-07"],"dc:date.issued":["2004-11-16"],"dc:description.abstract":["Solvation-thermodynamics models based on computational quantum mechanics, such as the conductor-like screening model (COSMO), provide a good alternative to traditional group-contribution methods for predicting thermodynamic phase behavior. Two COSMO-based thermodynamic models are COSMO-RS (real solvents) and COSMO-SAC (segment activity coefficient). The main molecule-specific input for these models is the sigma profile, or the probability distribution of a molecular surface segment having a specific charge density. Generating the sigma profiles represents the most time-consuming and computationally expensive aspect of using COSMO-based methods. A growing number of scientists and engineers are interested in the COSMO-based thermodynamic models, but are intimidated by the complexity of generating the sigma profiles. This thesis presents the first free, open-literature database of 1,513 self-consistent sigma profiles, together with two validation examples. The offer of these profiles will enable interested scientists and engineers to use the quantum-mechanics-based, COSMO methods without having to do quantum mechanics. This thesis summarizes the application experiences reported up to October 2004 to guide the use of the COSMO-based methods. 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