語系:
繁體中文
English
說明(常見問題)
回圖書館首頁
手機版館藏查詢
登入
回首頁
切換:
標籤
|
MARC模式
|
ISBD
FindBook
Google Book
Amazon
博客來
Topology and Electronic Properties of Low-Dimensional Carbon Materials.
紀錄類型:
書目-電子資源 : Monograph/item
正題名/作者:
Topology and Electronic Properties of Low-Dimensional Carbon Materials./
作者:
Jiang, Jingwei.
面頁冊數:
1 online resource (132 pages)
附註:
Source: Dissertations Abstracts International, Volume: 85-03, Section: B.
Contained By:
Dissertations Abstracts International85-03B.
標題:
Physics. -
電子資源:
http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30488437click for full text (PQDT)
ISBN:
9798380380744
Topology and Electronic Properties of Low-Dimensional Carbon Materials.
Jiang, Jingwei.
Topology and Electronic Properties of Low-Dimensional Carbon Materials.
- 1 online resource (132 pages)
Source: Dissertations Abstracts International, Volume: 85-03, Section: B.
Thesis (Ph.D.)--University of California, Berkeley, 2023.
Includes bibliographical references
In recent times, there has been a significant interest in low-dimensional materials due to their unique electronic, optical, magnetic, and topological properties that differ from 3D bulk materials. This dissertation focuses on a specific class of 1D carbon structures known as graphene nanoribbons (GNRs), which can be synthesized atomically with precision through a bottom-up method. The theoretical tools employed in this study are primarily topological theory and quantum many-body first-principles calculations.Chapter 1 introduces some basics about density functional theory, GW many-body perturbation theory and the Bethe-Salpeter equation. Chapter 2 of this dissertation delves into the topology of GNRs when chiral symmetry is approximately maintained. Building on this theory and in collaboration with experimentalists, Chapter 3 explores a metallic 1D nanowire known as saw-tooth GNRs, while Chapter 4 investigates various quantum dot systems with unique bonding and anti-bonding characters. In Chapter 5, a different type of metallic GNRs is studied using zero-mode (topologically protected in-gap electronic states) engineering. Chapter 6 takes the study beyond the Hermitian Hamiltonian and introduces the non-Hermitian skin effect. When 1D or 0D structures are interconnected, nanoporous graphene is formed. Its electronic properties are studied in Chapter 8. Furthermore, Chapter 9 examines a carbon kagome lattice's excitonic properties. The content of each Chapter is elaborated as the following:Chapter 1 provides a foundational understanding of density functional theory (DFT) for ground state properties by introducing the Kohn-Sham equation and different functionals. We also discuss the GW perturbation theory, which allows us to incorporate many-body effects into our calculations of excited-state properties. Specifically, we explore how the GW method can be utilized to calculate quasi-particle excitations. To study the two-particle excitation problem for optical properties, we introduce the Bethe-Salpeter equation (BSE) method. This equation provides a framework for calculating the interaction between an excited electron and the hole it leaves behind, which is crucial for understanding optical properties such as absorption and emission spectra.In Chapter 2, we examine GNR structures under the first nearest neighbor tight-binding model, assuming chiral symmetry holds. In this scenario, we utilize the first Chern number to obtain a Z index for general 1D materials. From the general Z index formula, we derive the Chiral phase index in vector form, which enables us to obtain the analytic Z index formula for all types of unit cells in GNRs. Finally, we explore a spin-chain formed by topological junction states that exhibit strong spin-spin interactions.Chapter 3 builds on the chiral classification theory introduced in Chapter 2 by utilizing the topological junction states as building blocks and connecting them in a symmetric manner to form a 1D metallic nanowire. We use first-principles DFT calculations to study the electronic bandstructure, local density of states (LDOS), and mapping of wavefunctions. Our results are then compared with experimental STM measurements, and we achieve good agreement. In addition, we also investigate the topological properties of asymmetrically connected structures, and the predicted junction/end state matches well the corresponding experimental evidence.In Chapter 4, we employed the topological junction states that arise from the connection between 7-armchair graphene nanoribbons (7AGNR) and 9-armchair graphene nanoribbons (9AGNR) to construct topological quantum dots. We investigated two distinct types of quantum dots by means of DFT calculations, with the aim of studying their electronic properties, such as the bonding and anti-bonding traits of their valence and conduction states. In addition, we devised a tight-binding theory to elucidate the underlying factors contributing to the characteristics of the wavefunctions.In Chapter 5, we focus on a different variety of metallic graphene nanoribbon (GNR) called Olympicene GNRs that does not exhibit the Stoner instability, which was observed in the sawtooth GNRs presented in Chapter 3. This new GNR features cove-shaped edges, and its low-energy behavior is governed by zero modes. The most notable distinction between this GNR and the sawtooth GNR is that the nearest zero modes localize on different sublattices, leading to a significant increase in electron hopping and precluding any magnetic instability. To verify this, we conduct DFT calculations and compare our findings with experimental observations.In Chapter 6, we explore the topology of 1D non-Hermitian systems, extending our analysis beyond Hermitian topological classification. Specifically, we investigate a 1D non-Hermitian system with no symmetry constraints, and use a Z index that can be employed to classify such systems. We examine the well-known skin effect for non-trivial non-Hermitian topological models and identify a promising GNR material, Co-4AGNR, which could potentially be realized in experiments. By conducting first-principles DFT and full-frequency GW calculations, we establish that the material exhibits non-trivial topology. Lastly, we present evidence of the asymmetric transport properties in this material by calculating the Green's function for a finite segment of this system.In Chapter 7, we examine the 2D carbon structure that results from linking 1D metallic GNRs. To accomplish this, we created a theoretical model with low energy states using modes that are found in the pentagons located at the edge of GNRs as the bases. This effective tight-binding model provides a description of a unique, distorted super-graphene. We also conducted DFT calculations and compared our findings with experimental results provided by our colleagues.Chapter 8 focuses on the examination of a kagome lattice that is formed by linking triangulene building blocks. This unique structure was predicted to exhibit excitonic insulator (EI) behavior. In partnership with experimentalists, we conducted an investigation of the electronic properties of this structure using multiple levels of theory, such as DFT, GW-BSE, and Bardeen-Cooper-Schrieffer (BCS) theory. Our research revealed that DFT based single-particle theory was insufficient for accurately capturing the features of the LDOS map observed in STM measurements. By incorporating a BCS-like theory for condensation of excitons, we were able to provide an explanation for the experimental observations.In addition to the projects above, I was also involved in 3 other projects, including one studying the color center in twisted BN [6], one studying the kondo effect in magnetic N-doped chevron GNR, one studying the pseudo-atomic orbitals in graphene nanoribbons [8]. These research projects are also very interesting, but beyond the scope of this dissertation.
Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2023
Mode of access: World Wide Web
ISBN: 9798380380744Subjects--Topical Terms:
516296
Physics.
Subjects--Index Terms:
Graphene nanoribbonsIndex Terms--Genre/Form:
542853
Electronic books.
Topology and Electronic Properties of Low-Dimensional Carbon Materials.
LDR
:08364nmm a2200409K 4500
001
2363960
005
20231127094745.5
006
m o d
007
cr mn ---uuuuu
008
241011s2023 xx obm 000 0 eng d
020
$a
9798380380744
035
$a
(MiAaPQ)AAI30488437
035
$a
AAI30488437
040
$a
MiAaPQ
$b
eng
$c
MiAaPQ
$d
NTU
100
1
$a
Jiang, Jingwei.
$3
3704739
245
1 0
$a
Topology and Electronic Properties of Low-Dimensional Carbon Materials.
264
0
$c
2023
300
$a
1 online resource (132 pages)
336
$a
text
$b
txt
$2
rdacontent
337
$a
computer
$b
c
$2
rdamedia
338
$a
online resource
$b
cr
$2
rdacarrier
500
$a
Source: Dissertations Abstracts International, Volume: 85-03, Section: B.
500
$a
Advisor: Louie, Steven G.
502
$a
Thesis (Ph.D.)--University of California, Berkeley, 2023.
504
$a
Includes bibliographical references
520
$a
In recent times, there has been a significant interest in low-dimensional materials due to their unique electronic, optical, magnetic, and topological properties that differ from 3D bulk materials. This dissertation focuses on a specific class of 1D carbon structures known as graphene nanoribbons (GNRs), which can be synthesized atomically with precision through a bottom-up method. The theoretical tools employed in this study are primarily topological theory and quantum many-body first-principles calculations.Chapter 1 introduces some basics about density functional theory, GW many-body perturbation theory and the Bethe-Salpeter equation. Chapter 2 of this dissertation delves into the topology of GNRs when chiral symmetry is approximately maintained. Building on this theory and in collaboration with experimentalists, Chapter 3 explores a metallic 1D nanowire known as saw-tooth GNRs, while Chapter 4 investigates various quantum dot systems with unique bonding and anti-bonding characters. In Chapter 5, a different type of metallic GNRs is studied using zero-mode (topologically protected in-gap electronic states) engineering. Chapter 6 takes the study beyond the Hermitian Hamiltonian and introduces the non-Hermitian skin effect. When 1D or 0D structures are interconnected, nanoporous graphene is formed. Its electronic properties are studied in Chapter 8. Furthermore, Chapter 9 examines a carbon kagome lattice's excitonic properties. The content of each Chapter is elaborated as the following:Chapter 1 provides a foundational understanding of density functional theory (DFT) for ground state properties by introducing the Kohn-Sham equation and different functionals. We also discuss the GW perturbation theory, which allows us to incorporate many-body effects into our calculations of excited-state properties. Specifically, we explore how the GW method can be utilized to calculate quasi-particle excitations. To study the two-particle excitation problem for optical properties, we introduce the Bethe-Salpeter equation (BSE) method. This equation provides a framework for calculating the interaction between an excited electron and the hole it leaves behind, which is crucial for understanding optical properties such as absorption and emission spectra.In Chapter 2, we examine GNR structures under the first nearest neighbor tight-binding model, assuming chiral symmetry holds. In this scenario, we utilize the first Chern number to obtain a Z index for general 1D materials. From the general Z index formula, we derive the Chiral phase index in vector form, which enables us to obtain the analytic Z index formula for all types of unit cells in GNRs. Finally, we explore a spin-chain formed by topological junction states that exhibit strong spin-spin interactions.Chapter 3 builds on the chiral classification theory introduced in Chapter 2 by utilizing the topological junction states as building blocks and connecting them in a symmetric manner to form a 1D metallic nanowire. We use first-principles DFT calculations to study the electronic bandstructure, local density of states (LDOS), and mapping of wavefunctions. Our results are then compared with experimental STM measurements, and we achieve good agreement. In addition, we also investigate the topological properties of asymmetrically connected structures, and the predicted junction/end state matches well the corresponding experimental evidence.In Chapter 4, we employed the topological junction states that arise from the connection between 7-armchair graphene nanoribbons (7AGNR) and 9-armchair graphene nanoribbons (9AGNR) to construct topological quantum dots. We investigated two distinct types of quantum dots by means of DFT calculations, with the aim of studying their electronic properties, such as the bonding and anti-bonding traits of their valence and conduction states. In addition, we devised a tight-binding theory to elucidate the underlying factors contributing to the characteristics of the wavefunctions.In Chapter 5, we focus on a different variety of metallic graphene nanoribbon (GNR) called Olympicene GNRs that does not exhibit the Stoner instability, which was observed in the sawtooth GNRs presented in Chapter 3. This new GNR features cove-shaped edges, and its low-energy behavior is governed by zero modes. The most notable distinction between this GNR and the sawtooth GNR is that the nearest zero modes localize on different sublattices, leading to a significant increase in electron hopping and precluding any magnetic instability. To verify this, we conduct DFT calculations and compare our findings with experimental observations.In Chapter 6, we explore the topology of 1D non-Hermitian systems, extending our analysis beyond Hermitian topological classification. Specifically, we investigate a 1D non-Hermitian system with no symmetry constraints, and use a Z index that can be employed to classify such systems. We examine the well-known skin effect for non-trivial non-Hermitian topological models and identify a promising GNR material, Co-4AGNR, which could potentially be realized in experiments. By conducting first-principles DFT and full-frequency GW calculations, we establish that the material exhibits non-trivial topology. Lastly, we present evidence of the asymmetric transport properties in this material by calculating the Green's function for a finite segment of this system.In Chapter 7, we examine the 2D carbon structure that results from linking 1D metallic GNRs. To accomplish this, we created a theoretical model with low energy states using modes that are found in the pentagons located at the edge of GNRs as the bases. This effective tight-binding model provides a description of a unique, distorted super-graphene. We also conducted DFT calculations and compared our findings with experimental results provided by our colleagues.Chapter 8 focuses on the examination of a kagome lattice that is formed by linking triangulene building blocks. This unique structure was predicted to exhibit excitonic insulator (EI) behavior. In partnership with experimentalists, we conducted an investigation of the electronic properties of this structure using multiple levels of theory, such as DFT, GW-BSE, and Bardeen-Cooper-Schrieffer (BCS) theory. Our research revealed that DFT based single-particle theory was insufficient for accurately capturing the features of the LDOS map observed in STM measurements. By incorporating a BCS-like theory for condensation of excitons, we were able to provide an explanation for the experimental observations.In addition to the projects above, I was also involved in 3 other projects, including one studying the color center in twisted BN [6], one studying the kondo effect in magnetic N-doped chevron GNR, one studying the pseudo-atomic orbitals in graphene nanoribbons [8]. These research projects are also very interesting, but beyond the scope of this dissertation.
533
$a
Electronic reproduction.
$b
Ann Arbor, Mich. :
$c
ProQuest,
$d
2023
538
$a
Mode of access: World Wide Web
650
4
$a
Physics.
$3
516296
650
4
$a
Materials science.
$3
543314
650
4
$a
Atomic physics.
$3
3173870
650
4
$a
Computational physics.
$3
3343998
653
$a
Graphene nanoribbons
653
$a
Low-dimensional materials
653
$a
Topology
653
$a
Kagome lattice
653
$a
Triangulene building blocks
655
7
$a
Electronic books.
$2
lcsh
$3
542853
690
$a
0605
690
$a
0794
690
$a
0216
690
$a
0748
710
2
$a
ProQuest Information and Learning Co.
$3
783688
710
2
$a
University of California, Berkeley.
$b
Physics.
$3
1671059
773
0
$t
Dissertations Abstracts International
$g
85-03B.
856
4 0
$u
http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30488437
$z
click for full text (PQDT)
筆 0 讀者評論
館藏地:
全部
電子資源
出版年:
卷號:
館藏
1 筆 • 頁數 1 •
1
條碼號
典藏地名稱
館藏流通類別
資料類型
索書號
使用類型
借閱狀態
預約狀態
備註欄
附件
W9486316
電子資源
11.線上閱覽_V
電子書
EB
一般使用(Normal)
在架
0
1 筆 • 頁數 1 •
1
多媒體
評論
新增評論
分享你的心得
Export
取書館
處理中
...
變更密碼
登入