Excited-State Properties of Electrostatically Doped Low-Dimensional Structures

技术总结该奖项支持计算和理论研究以及教育，以研究掺杂对人们广泛关注的低维结构激发态性质的影响，包括硅纳米线、石墨烯和电栅双层石墨烯。由于这些结构的几何结构和靠近能带边缘的电子态密度的相关发散，静电掺杂的自由载流子可以极大地改变多电子相互作用的电子屏蔽。因此，即使是少量的掺杂也可能极大地改变激发态的性质，如准粒子的带隙和光学性质，使得掺杂除了通常提供自由载流子的作用外，还成为调节低维材料本征电子结构的有效工具。多电子效应的变化也可能改变自旋单重态-三重态的分裂，从而改变发光性质，从而有可能应用于量子信息技术。这项研究涉及使用基于密度泛函理论的方法，以及GW和Bethe-Salpeter方程的解。该奖项还支持教育活动，包括在华盛顿大学开设的一门新课程--第一原理计算及其在纳米结构中的应用。其他活动包括为来自附近研究所的感兴趣的研究人员举办一系列研讨会，介绍尖端的第一原则方法及其在纳米技术中的应用。非技术总结该奖项支持计算和理论研究以及教育，以研究非常微小的导线的性质，这些导线只有几个原子宽，单原子厚的碳片，被称为石墨烯。PI将使用先进的计算方法，旨在从原子和材料的组成原子的知识开始预测原子和材料的结构性质。特别令人感兴趣的是涉及原子的材料和结构吸收或发射光线的性能。这项工作的目的是确定如何使用量子线或石墨烯中的添加和移除电子来设计量子线和石墨烯的量子力学状态。该项目为知识库做出了贡献，其中包括未来设备技术将基于的方法和软件。这项工作的具体方面有助于设计有效地将光转化为电能的光伏装置。该奖项还支持教育活动，包括在华盛顿大学开设的新课程《第一性原理计算及其在纳米结构中的应用》。其他活动包括为来自附近研究所的感兴趣的研究人员举办一系列研讨会，介绍尖端的第一原则方法及其在纳米技术中的应用。

TECHNICAL SUMMARYThis award supports computational and theoretical research and education to study doping effects on excited-state properties of low-dimensional structures of broad interest, including silicon nanowires, graphene and electrically gated bilayer graphene. Because of the geometry of these structures and the associated divergence of the electronic density of states close to the band edge, electrostatically doped free carriers can dramatically change the electronic screening of many-electron interactions. As a result, an even small amount of doping may substantially change the excited-state properties, such as the quasiparticle band gap and optical properties, making doping an efficient tool to tune the intrinsic electronic structure of low-dimensional materials in addition to its usual role of providing free carriers. The variation of many-electron effects may also modify the spin singlet-triplet splitting which would change the luminescence properties with possible application to quantum information technology. The research involves using density functional theory based methods along with GW and the solution of the Bethe-Salpeter equation.This award also supports educational activities, including a new course, 'First-Principles Calculations and Their Applications to Nanostructures,' in Washington University. Additional activities include a series of seminars for interested researchers from institutes nearby to introduce cutting-edge first-principles approaches and their applications to the nanotechnology. NONTECHNICAL SUMMARYThis award supports computational and theoretical research and education to investigate the properties of very tiny wires that are little more than a few atoms wide and single-atom thick carbon sheets known as graphene. The PI will use advanced computational methods that aim to predict properties of structures of atoms and materials starting from knowledge of their constituent atoms. Of particular interest are properties that involve how well materials and structures of atoms absorb or emit light. An aim of the work is to determine how the addition and removal electrons from the quantum wires or graphene can be used to design the quantum mechanical states of quantum wires and graphene. This project contributes to the knowledge base including methods and software upon which future device technologies will be based. Specific aspects of the work contribute to the design of photovoltaic devices for the efficient conversion of light to electricity. This award also supports educational activities, including a new course, 'First-Principles Calculations and Their Applications to Nanostructures,' in Washington University. Additional activities include a series of seminars for interested researchers from institutes nearby to introduce cutting-edge first-principles approaches and their applications to the nanotechnology.