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Description
Title: | Development of non-born-Oppenheimer methods for ground and excited state molecular properties |
Author(s): | Culpitt, Tanner P. |
Director of Research: | Hammes-Schiffer, Sharon |
Doctoral Committee Chair(s): | Makri, Nancy |
Doctoral Committee Member(s): | Vura-Weis, Joshua; Wagner, Lucas |
Department / Program: | Chemistry |
Discipline: | Chemistry |
Degree Granting Institution: | University of Illinois at Urbana-Champaign |
Degree: | Ph.D. |
Genre: | Dissertation |
Subject(s): | electronic structure
non-Born-Oppenheimer DFT TDDFT Wave Function |
Abstract: | The nuclear-electronic orbital (NEO) method is a multicomponent approach that allows the quantum mechanical treatment of electrons and specified protons on the same quantum mechanical level. NEO does not make the Born-Oppenheimber approximation between electrons and select protons, and therefore has great potential in applications to non-Born-Oppenheimer processes such as proton-coupled electron transfer (PCET). Additionally, NEO can also capture nuclear quantum effects such as zero-point energy and proton delocalization in a direct and efficient manner. This dissertation describes the development of NEO methods for calculating both ground and excited state molecular properties. For the ground state, a general multicomponent embedding scheme is developed and tested within the NEO framework to obtain nuclear densities. Machinery is also presented for identifying the character and stability of NEO self-consistent field (SCF) solutions, allowing the differentiation between minima and saddle points. For excited states, the linear response multicomponent time-dependent density functional theory (TDDFT) is derived and implemented within the NEO framework. The results for nuclear vibrational excitations of interest corresponding to single or multiple protons calculated with NEO-TDDFT are accurate when the method is used in conjunction with large nuclear and electronic basis sets. Lastly, a scheme is presented for coupling proton vibrational excitation energies calculated with NEO-TDDFT to the normal modes associated with the other nuclei. This scheme, denoted NEO-DFT(V), thereby allows for full molecular vibrational frequencies to be calculated. These NEO methods provide the foundation for a wide range of applications, especially those involving non-Born-Oppenheimber processes or nuclear quantum effects. |
Issue Date: | 2019-10-17 |
Type: | Text |
URI: | http://hdl.handle.net/2142/106433 |
Rights Information: | Copyright 2019 Tanner Culpitt |
Date Available in IDEALS: | 2020-03-02 |
Date Deposited: | 2019-12 |
This item appears in the following Collection(s)
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Dissertations and Theses - Chemistry
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Graduate Dissertations and Theses at Illinois
Graduate Theses and Dissertations at Illinois