Database of Dopants and Defects in 2D Materials

该EAGER奖项支持二维材料的计算研究和二维材料数据资源的开发，该资源将通过宾夕法尼亚州立大学的二维晶体联盟（2DCC）材料创新平台提供。石墨烯可能是最著名的二维材料，它是一个单原子厚的六边形“铁丝网”，每个角都有一个碳原子。石墨烯具有奇异的电子特性，包括电子的行为就像它们以光速运动一样，导电能力比铜好100万倍。其他包含原子薄层的二维材料已经被开发出来。这些都是本研究项目的重点，包括过渡金属二硫族化合物。过渡金属二硫化物包含元素周期表中过渡金属列中的一个金属原子，如钨或钼，以及原始单元中的两个硫原子或硒原子，通过复制和平移来填充空间，确定其结构。过渡金属二硫族化合物与石墨烯的不同之处在于，它们的电子特性有一些类似于硅的特征，例如硅是半导体，而石墨烯是半金属。它们还具有许多有趣和更奇特的电子特性。过渡金属二硫族化合物和相关化合物的这些性质使它们成为发现新的物理效应和新的电子和光学器件技术的有希望的候选者，并成为许多研究的主题。PI将修改他开发的用于并行快速计算许多材料特性的软件，使其能够计算二维材料。使用该软件，将对由于额外的杂质原子、缺失原子或结构原子排列中的其他缺陷而导致组成原子的排列偏离完美材料结构的二维材料的性质进行高质量的计算。这些信息将被收集并提供给一个数据库，供更广泛的社区访问，特别是对使用2DCC材料创新平台的研究人员。了解改变带电粒子浓度的缺陷和杂质的作用，这些带电粒子可以携带电流，否则会改变大块硅的性质，这对晶体管的发展非常重要。获得该奖项提供的数据可能会对2D材料在新的基础科学发现和新的电子或光电器件的发明方面产生类似的变革性影响。该项目将与2DCC一起及时解决社区对缺陷、掺杂剂和杂质在2D材料中所起作用的信息日益增长的需求，以帮助指导实验和理论工作。项目期间创建的软件、文档和数据可以应用于其他环境，并将作为材料研究社区网络基础设施的一部分免费提供给更广泛的社区。数据将通过MaterialsWeb数据库提供。该项目将有助于培训下一代计算研究人员，以促进未来网络基础设施的发展。与德国研究人员的合作将有助于参与该项目的学生的教育。该EAGER奖项支持二维材料和网络基础设施开发的计算研究，可通过宾夕法尼亚州立大学二维晶体联盟（2DCC）材料创新平台获得。随着二维材料的合成和应用的不断发展，需要了解掺杂剂和缺陷如何控制二维材料的载流子浓度、性质和迁移率。就像在块状半导体中一样，二维材料中的掺杂剂和缺陷经常带电。了解它们的形成能和电荷跃迁能级对于设计新型二维材料电子和自旋电子器件至关重要。开发二维材料中缺陷和掺杂物特性的数据库有可能彻底改变二维电子设备的设计，就像块状半导体的类似数据一样。密度泛函理论采用精确的混合交换相关泛函提供了一种工具，可以预测地层能量和电荷跃迁水平，精度达到0.1 - 0.2 eV，足以用于电子设备设计。然而，单层材料中的带电缺陷挑战了传统的计算方法，如使用平面波方法的密度泛函理论计算，并导致能量随真空间距的发散。采用广义偶极子方法并恢复带电二维材料的适当静电边界条件的校正方案将耦合到PI基于python的高通量框架mpinterface中。这将使广泛使用的二维材料（如石墨烯、磷烯、金属二硫族化合物和单硫族化合物）的缺陷和掺杂性质数据库快速发展。然后将这种方法应用于2DCC用户感兴趣的材料，然后应用于整个MaterialsWeb数据库。结果将通过我们的MaterialsWeb数据库免费提供。该项目将与2DCC一起及时解决社区对缺陷、掺杂剂和杂质在2D材料中所起作用的信息日益增长的需求，以帮助指导实验和理论工作。项目期间创建的软件、文档和数据可以应用于其他环境，并将作为材料研究社区网络基础设施的一部分免费提供给更广泛的社区。数据将通过MaterialsWeb数据库提供。该项目将有助于培训下一代计算研究人员，以促进未来网络基础设施的发展。与德国研究人员的合作将有助于参与该项目的学生的教育。

NONTECHNICAL SUMMARYThis EAGER award supports computational research on two-dimensional materials and the development of a 2D materials data resource that will be made available through the 2-Dimensional Crystal Consortium (2DCC) Materials Innovation Platform at Pennsylvania State University. Graphene is perhaps the most famous of the 2D materials being a one-atom thick mesh of hexagonal "chicken wire" with a carbon atom at each corner. Graphene has exotic electronic properties, including electrons that behave as though they traveled at the speed of light and an ability to conduct electricity some 1,000,000 times better than copper. Other 2D materials that contain atomically thin layers have been developed. These are the focus of this research project and include transition-metal dichalcogenides. A transition-metal dichalcogenide contains a metal atom from the transition metal columns of the periodic table of elements, like tungsten, or molybdenum, and two chalcogen atoms like sulfur or selenium in the primitive unit that upon replication and translation to fill space defines its structure. Transition-metal dichalcogenides differ from graphene in that their electronic properties have some features akin to silicon, which for example is a semiconductor whereas graphene is a semimetal. They also have a host of interesting and more exotic electronic properties. These properties taken together for transition-metal dichalcogenides and related compounds make them promising candidates for the discovery of fundamentally new physical effects and new electronic and optical device technologies, and the subject of much research. The PI will modify software that he has developed for the rapid calculation of the properties of many materials in parallel to enable calculations for 2D materials. Using this software, high quality calculations will be performed for the properties of 2D materials for which the arrangement of the constituent atoms deviates from the structure of a perfect materials because of additional impurity atoms, missing atoms, or other defects in the structural atomic arrangement. This information will be collected and served in a database that is accessible to the broader community, particularly to researchers that use the 2DCC Materials Innovation Platform. Understanding the role of defects and impurities that change the concentration of charged particles that can carry current and otherwise alter the properties of bulk silicon was important in the development of the transistor. Ready access to the data provided under this award may have a similar transformative effect for 2D materials in new fundamental science discoveries and in the invention of new electronic or optoelectronic devices. This project in conjunction with 2DCC would address in a timely way, the growing needs of the community for information on the role defects, dopants, and impurities play in 2D materials to help guide experimental and theoretical efforts. Software, documentation, and data created during the project could be applied in other contexts and will be made freely available to the broader community as part of the materials research community cyberinfrastructure. Data will be made available through the MaterialsWeb database. The project will contribute to the training of the next generation of computational researchers to enable the development of future cyberinfrastructure. Collaboration with researchers in Germany will contribute to the education of the students participating in this project.TECHNICAL SUMMARYThis EAGER award supports computational research on two-dimensional materials and cyberinfrastructure development to be made available through 2-Dimensional Crystal Consortium (2DCC) Materials Innovation Platform at Pennsylvania State University. Progress in the synthesis and application of 2D materials as pursued by the 2DCC requires understanding how dopants and defects control the carrier concentration, character, and mobility of 2D materials. Just like in bulk semiconductors, dopants and defects in 2D materials are frequently charged. Understanding their formation energies and charge transition levels is crucial for the design of novel 2D-materials-based electronic and spintronic devices. Developing a database of the properties of defects and dopants in 2D materials has the potential to revolutionize the design of 2D electronic devices, the way analogous data did for bulk semiconductors. Density-functional theory employing accurate hybrid exchange-correlation functionals provides a tool that can predict formation energies and charge transition levels to an accuracy of 0.1 - 0.2 eV, sufficient for electronic device design. However, charged defects in single-layer materials challenge conventional computational approaches such as density-functional theory calculations using plane-wave approaches and lead to the divergence of the energy with vacuum spacing. A correction scheme that employs a generalized dipole approach and restores the appropriate electrostatic boundary conditions for charged 2D materials will be coupled in to the PI's Python-based high-throughput framework MPInterfaces. This will enable the rapid development of the database of defect and dopant properties for widely-used 2D materials, such as graphene, phosphorene, metal dichalcogenides, and monochalcogenides. This approach will then be applied to materials of interest to users of the 2DCC and then to the complete MaterialsWeb database. The results will be made freely available through our MaterialsWeb database.This project in conjunction with 2DCC would address in a timely way, the growing need of the community for information on the role defects, dopants, and impurities play in 2D materials to help guide experimental and theoretical efforts. Software, documentation, and data created during the project could be applied in other contexts and will be made freely available to the broader community as part of the materials research community cyberinfrastructure. Data will be made available through the MaterialsWeb database. The project will contribute to the training of the next generation of computational researchers to enable the development of future cyberinfrastructure. Collaboration with researchers in Germany will contribute to the education of the students participating in this project.