自旋电子学是基于对电子的自旋属性调控从而实现信息的处理和存储等目标而发展的新兴学科。与以电荷属性为基础的传统电子学器件和材料相比，自旋电子学器件和材料具有低功耗、非易失性、高速等优点而具有重要的应用前景。在理论研究中，双探针系统被广泛用于描述分子器件和纳米器件。许多研究表明，纳米器件的输运特性不仅取决于所采用的纳米材料，而且还取决于电极及其之间的耦合。本文主要对低维纳米结模型器件中的电荷和自旋输运进行了理论研究。在简要回顾纳米器件中量子传输的基本理论方法后，深入探讨了分子器件中的开关比、自旋过滤以及自旋极化等，并给出相应的输运量子调控的理论机理。

Chapter 1 Introduction
Chapter 2 Basic theories for quantum transport
2.1 Born-Oppenheimer approximation
2.2 Molecular dynamic simulation
2.2.1 Classical molecular dynamics
2.2.2 Ab initio molecular dynamics
2.2.3 Particle statistics
2.3 Electronic structure methods
2.3.1 Hartree-fock method
2.3.2 Density functional theory
2.4 General transport theory
2.4.1 Drude model
2.4.2 Boltzmann transport equation
2.4.3 Linear response transport theory
2.4.4 Quantum transport theory
2.4.5 Landauer approach
2.4.6 Lippmann-Schwinger equation
2.4.7 Non-equilibrium Green's function approach
Chapter 3 Electronic structures and transport properties of low-dimensional GaN nanoderivatives: a first-principles study
3.1 Introduction
3.2 Sample structure and computational details
3.3 Results and discussions
3.3.1 Electronic structures of two-dimensional bilayer GaN structures
3.3.2 Transport characteristics of one-dimensional GaN devices
3.4 Conclusion
Chapter 4 Length-independent multifunctional device based on penta-tetra-pentagonal molecule: a first-principles study
4.1 Introduction
4.2 Model and method
4.3 Result and discussion
4.4 Summary and conclusion
Chapter 5 Modulating the properties of multi-functional molecular devices consisting of zigzag gallium nitride nanoribbons by different magnetic orderings: a first-principles study
5.1 Introduction
5.2 Models and methods
5.3 Results and discussion
5.4 Conclusions
Chapter 6 Modulation of electrical performance of zigzag edged tetra-penta-octagonal graphene nanoribbons based devices via
boundary passivations
6. 1 Introduction
6.2 Sample structure and computational details
6. 3 Results and discussion
6. 3.1 Electronic structures of TPO-zGNRs-H
6. 3.2 Electronic properties of TPO-zGNRs-X
6. 3.3 Transport properties of TPO-zGNRs-X model devices
6. 3.4 An obvious rectification and NDR effects in TPO-zGNRs-H/O model device
6.4 Conclusions
Chapter 7 Direction and strain controlled anisotropic transport behaviors of 2D GeSe-phosphorene vdW heterojunctions
7.1 Introduction
7.2 Sample structure and computational details
7.3 Results and discussion
7.4 Conclusions
Chapter 8 Carbon phosphide nanosheet and nanoribbon: insights on modulating their electronic properties by first principles
calculations
8.1 Introduction
8.2 Model and methods
8.3 Results and discussion
8.4 Conclusions
Chapter 9 High-performance spin rectification in gallium nitride- based molecular junctions with asymmetric edge passivation
9.1 Introduction
9.2 Models and methods
9.3 Results and discussion
9.3.1 Edge-passivation spin transmission
9.3.2 Width-independent rectification behavior
9.4 Conclusions
9.5 Supplementary material
Chapter 10 Modulation of electronic structure properties of C/B/AI-doped armchair GaN nanoribbons
10.1 Introduction
10.2 Model and method
10.3 Results and discussion
10.4 Conclusion
Chapter 11 Investigation of the electronic and magnetic properties of low-dimensional FeCl2 derivatives by first-principles
calculations
11.1 Introduction
11.2 Computational details
11.3 Results and discussion
11.4 Conclusions
Chapter 12 Modulation of electronic behaviors of InSe nanosheet and nanoribbons: the first-principles study
12.1 Introduction
12.2 Computational details
12.3 Results and discussion
12.3.1 Electronic structures of InSe nanosheet
12.3.2 Electronic structures of InSe nanoribbon
12.3.3 Electronic transport properties of zISNs
12.4 Conclusions
12.5 Supplementary material
References
Acknowledgement