Material Type  

 학위논문

 

0017160958

Date and Time of Latest Transaction  

20250211151141

ISBN  

9798382715612

DDC  

540

Author  

Shepard, Christopher.

Title/Author  

First Principles Study of Nonequilibrium Electron Dynamics in Complex Extended Systems Using Time-Dependent Maximally Localized Wannier Functions.

Publish Info  

[S.l.] : The University of North Carolina at Chapel Hill., 2024

Publish Info  

Ann Arbor : ProQuest Dissertations & Theses, 2024

Material Info  

230 p.

General Note  

Source: Dissertations Abstracts International, Volume: 85-11, Section: B.

General Note  

Advisor: Kanai, Yosuke.

학위논문주기  

Thesis (Ph.D.)--The University of North Carolina at Chapel Hill, 2024.

Abstracts/Etc  

요약Developing a complete picture of the underlying electron dynamics is essential for understanding the details of numerous physical processes, including electronic stopping and optical excitation, among others. First-principles approaches offer a pathway to unravel the quantum details of these processes without reliance on any empirical data. Real-time time-dependent density functional theory (RT-TDDFT) stands out as a proficient tool, adept at accurately and efficiently simulating electron dynamics across diverse systems. Nonetheless, the molecular-level details of many electronic excitation processes remain unknown, especially for extended systems.In this dissertation we investigate the molecular-level details of various electronic dynamic phenomena using RT-TDDFT. Much of this dissertation is centered on electronic stopping in complex extended biological systems, with a specific emphasis on its application to ion beam therapy. Electronic stopping entails the transfer of energy from high energy ions, such as protons, to the electrons of a target material. The energy deposition profile is highly localized, leading to considerable attention from the medical physics community and beam therapies emergence as a viable alternative to traditional X-ray oncology cancer treatments. Using RT-TDDFT simulation we examine the electronic stopping process in both liquid water and solvated DNA to understand and build a complete picture of the ultrafast electronic response. We unveil key details of the stopping process, including how the primary excitation by an irradiating proton in liquid water precedes the formation of cationic holes. With the help of supercomputers, we compare the electronic stopping process in solvated DNA under proton, α-particle, and carbon ion irradiation. We show how significantly more energy is deposited on the sugar-phosphate side chains through the formation of highly energetic holes, leading to DNA strand damage and cell death.The concluding section of this dissertation covers technical advancements in RT-TDDFT, focusing primarily on accelerating calculations utilizing exact exchange through the implementation of time-dependent maximally localized Wannier functions (TD-MLWFs). Additionally, we detail several related advancements, including the refinement procedure for TD-MLWFs, comparison of the velocity and length gauge approaches for modeling an electric field, and usage of a complex absorbing potential for modeling isolated systems in the planewave-pseudopotential formalism of RT-TDDFT.

Subject Added Entry-Topical Term  

Chemistry.

Subject Added Entry-Topical Term  

Physics.

Subject Added Entry-Topical Term  

Physical chemistry.

Index Term-Uncontrolled  

Electronic stopping

Index Term-Uncontrolled  

First principles simulations

Index Term-Uncontrolled  

Wannier functions

Index Term-Uncontrolled  

Electron dynamics

Index Term-Uncontrolled  

Energetic holes

Added Entry-Corporate Name  

The University of North Carolina at Chapel Hill Chemistry

Host Item Entry  

Dissertations Abstracts International. 85-11B.

Electronic Location and Access  

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Control Number  

joongbu:656173