2026-09-19T05:51:12Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/731752022-01-13T07:54:21Zcom_1721.1_7582com_1721.1_7581col_1721.1_131022
Troy Van Voorhis.
Kaduk, Benjamin James
Massachusetts Institute of Technology. Dept. of Chemistry.
Massachusetts Institute of Technology. Department of Chemistry
2012-09-26T14:17:40Z
2012-09-26T14:17:40Z
2012
2012
http://hdl.handle.net/1721.1/73175
809542537
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2012.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (p. 117-136).
In this thesis, I implemented a method for performing electronic structure calculations, "Constrained Density Functional Theory-- Configuration Interaction" (CDFT-CI), which builds upon the computational strengths of Density Functional Theory and improves upon it by including higher level treatments of electronic correlation which are not readily available in Density-Functional Theory but are a keystone of wavefunction-based electronic structure methods. The method involves using CDFT to construct a small basis of hand-picked states which suffice to reasonably describe the static correlation present in a particular system, and efficiently computing electronic coupling elements between them. Analytical gradients were also implemented, involving computational effort roughly equivalent to the evaluation of an analytical Hessian for an ordinary DFT calculation. The routines were implemented within Q-Chem in a fashion accessible to end users; calculations were performed to assess how CDFT-CI improves reaction transition state energies, and to assess its ability to produce conical intersections, as compared to ordinary DFT. The analytical gradients enabled optimization of reaction transition-state structures, as well as geometry optimization on electronic excited states, with good results.
by Benjamin James Kaduk.
Ph.D.
136 p.
eng
Massachusetts Institute of Technology
M.I.T. theses are protected by
copyright. They may be viewed from this source for any purpose, but
reproduction or distribution in any format is prohibited without written
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http://dspace.mit.edu/handle/1721.1/7582
Chemistry.
Constrained Density-Functional Theory--Configuration Interaction
Constrained DFT--Configuration Interaction
CDFT-CI
Thesis
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<Abstract>In this thesis, I implemented a method for performing electronic structure calculations, "Constrained Density Functional Theory-- Configuration Interaction" (CDFT-CI), which builds upon the computational strengths of Density Functional Theory and improves upon it by including higher level treatments of electronic correlation which are not readily available in Density-Functional Theory but are a keystone of wavefunction-based electronic structure methods. The method involves using CDFT to construct a small basis of hand-picked states which suffice to reasonably describe the static correlation present in a particular system, and efficiently computing electronic coupling elements between them. Analytical gradients were also implemented, involving computational effort roughly equivalent to the evaluation of an analytical Hessian for an ordinary DFT calculation. The routines were implemented within Q-Chem in a fashion accessible to end users; calculations were performed to assess how CDFT-CI improves reaction transition state energies, and to assess its ability to produce conical intersections, as compared to ordinary DFT. The analytical gradients enabled optimization of reaction transition-state structures, as well as geometry optimization on electronic excited states, with good results.</Abstract>
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