Title

A first-principles study of the various properties induced by interlayer interactions through 1T-TaS2 and cellulose nanocrystal cases

Alternative Title

1T-TaS2 와 cellulose nanocrystal 을 통해 살펴본 제일 원리 계산을 활용한 층간 상호작용에 의해 나타나는 다양한 물성 연구

DGIST Authors

Juhyung Lee ; Joongoo Kang ; Junhyeok Bang

Advisor

강준구

Co-Advisor(s)

Junhyeok Bang

Issued Date

2024

Awarded Date

2024-02-01

Citation

Juhyung Lee. (2024). A first-principles study of the various properties induced by interlayer interactions through 1T-TaS2 and cellulose nanocrystal cases. doi: 10.22677/THESIS.200000725006

Type

Thesis

Description

범밀도함수론 (DFT);전하밀도파 (CDW);층간 상호작용;셀룰로오스 나노 결정;이차원 전이금속 칼코겐화합물 (2D-TMD)

Table Of Contents

Abstract i
List of Contents ii
List of tables iii
List of figures vi

I. Introduction 1
1.1 Interlayer interaction 1
1.1.1 Interlayer interaction in the heterojunction of 2D transition metal dichalcogenides 2
1.1.2 Interlayer electron transport 3
1.2 Charge density wave 5
1.2.1 The various patterns of crystals caused by charge density wave 6
1.2.2 The phase transition of 1T-TaS2 by the CDW distortion 9
1.3 Cellulose nanocrystal 10
1.3.1 The simulation of cellulose nanocrystals 17
1.4 Surface transfer doping 19

II. Theoretical Frameworks 21
2.1 Density functional theory (DFT) 21
2.1.1 Many-body Schrödinger equation 23
2.1.2 Mean-field approximation 26
2.1.3 Hartree-Fock approximation 28
2.1.4 Kohn-Sham equation 29
2.1.5 Local-density approximation & generalized gradient approximation 30
2.1.6 Modern DFT algorithm 32
2.1.7 Basis set 33

2.1.7.1 Linear combination of atomic orbitals (LCAO) 34
2.1.7.2 Projector augmented plane wave method (PAW) 34
2.1.8 Time dependent density functional theory (TDDFT) 35

III. Results and discussions I: 1T-TaS2 case 38
3.1 1T-TaS2 structural optimization & 1T-TaS2 /MX2 model construction 38
3.1.1 1T-TaS2 structural optimization 39
3.1.2 The MX2 candidates for 1T-TaS2 /MX2 model 41
3.2 The photoexcitation of 1T-TaS2 /MX2 model 43
3.2.1 The ultrafast phase transition transfer dynamics of 1T-TaS2 monolayer 45
3.2.2 The ultrafast phase transition transfer dynamics of 1T-TaS2 /MX2 model 46
3.3 Conclusion 51

IV. Results and discussions II: Cellulose nanocrystal case 52
4.1 Structural optimization 52
4.2 Optical and electric properties of cellulose nanocrystal 56
4.2.1 Optical properties of cellulose nanocrystal 57
4.2.2 Electric properties of cellulose nanocrystal 61
4.3 Doping methods of cellulose nanocrystal 63
4.3.1 p-type doping method 66
4.3.1.1 F4-TCNQ families 67
4.3.1.1.1 Molecular doping 68
4.3.1.1.2 Crystal doping 69
4.3.1.2 CN6-CP 72
4.3.2 n-type doping method 73
4.3.2.1 Intercalation 74
4.3.2.2 Surface functionalization of cellulose nanocrystal 78
4.3.2.2.1 Halogens 78
4.3.2.2.2 Others 81

4.4 Conclusion 82

V. References 84

VI. Korean summary 98

URI

http://hdl.handle.net/20.500.11750/48044
http://dgist.dcollection.net/common/orgView/200000725006

DOI

10.22677/THESIS.200000725006

Degree

Doctor

Department

Department of Physics and Chemistry

Publisher

DGIST

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