Beyond DFT: Accurate Simulations of Low Dimensional Materials For Energy and Device Applications

该奖项支持理论和计算研究，重点是推进对二维材料的理解。二维（2D）材料具有非凡的性能。它们是有史以来发现的最强的材料之一，可以从金属变成半导体，反之亦然，只需将它们堆叠在层中，拉伸或掺杂它们。这指出了2D材料在储能、电池和半导体器件中的潜在应用。研究小组将使用高度精确的模拟技术，称为量子蒙特卡罗方法，来阐明有趣的无机2D材料，过渡金属二硫属化物和后过渡金属硫属化物的性质。根据发现的材料特性，该团队的目标是“设计”和建模新的2D材料，适用于能够超越传统设备的电子设备，并利用光分裂水分子以获取氢气作为能源。该奖项还支持该团队通过大学申请和年度科学博览会流程指导服务不足地区学生的努力，并教育多元化的年轻科学家了解物理科学，作为当地服务不足人群的推广工作的一部分，包括当地高中女孩谁代码俱乐部。 该奖项支持理论和计算研究，重点是推进对二维材料的理解。量子限制极限内的二维（2D）无机材料正在成为一类重要的纳米材料，用于信息技术、光电子学、自旋电子学以及能量存储和转换技术中的新应用。由于增强的量子限制和高表面积与体积比的影响，低维材料具有非凡的化学和物理性质，包括带隙和金属-半导体转变，其性质可以通过改变其掺杂和分层来调整。因此，它们的范围可以从绝缘体到拓扑绝缘体到半导体，甚至超导体。因此，了解这些材料的性质提出了一个材料研究的机会，可能有直接的重要性，未来的半导体器件的设计。该团队的目标是开发高精度的方法，以克服基于密度泛函的第一原理方法的局限性，特别是在其应用于2D材料时，以更好地理解实验。该方法的开发涉及到结合量子蒙特卡罗与通常用于模拟合金的团簇展开方法。该团队将使用这些方法来研究从金属到间隙半导体的后过渡金属硫属化物的单层/多层结构。直接间隙化合物的光电化学和光电化学水裂解应用将设计使用合金化作为一种手段来调整相稳定性，电子和光学性能。 PI将利用这项研究来教育不同的年轻科学家关于物理科学的身体，作为当地外展工作的一部分，以服务不足的人群，包括当地的高中女孩谁代码俱乐部。这个奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

NONTECHICAL SUMMARYThis award supports theoretical and computational research focused on advancing understanding of two-dimensional materials. Two-dimensional (2D) materials possess extraordinary properties. They are among the strongest materials ever discovered and can change from metals to semiconductors and vice-versa just by stacking them in layers, stretching, or doping them. This points to the potential applications of 2D materials in energy storage, batteries, and semiconductor devices. The research team will use highly accurate simulation techniques, called quantum Monte Carlo methods, to illuminate the properties of interesting inorganic 2D materials, the transition metal dichalcogenides and the post-transition metal chalcogenides. Based upon the material properties uncovered, the team aims to "engineer" and model new 2D-materials suitable for electronic devices capable of outperforming traditional devices and using light to split the water molecule to harvest hydrogen for energy. This award also supports the team's efforts to mentor underserved area students through the college applications and annual science fair processes, and to educate a diverse body of younger scientists about the physical sciences as part of local outreach efforts to underserved populations, including local high school Girls Who Code Clubs. TECHNICAL SUMMARYThis award supports theoretical and computational research focused on advancing understanding of two-dimensional materials. Two-dimensional (2D) inorganic materials within the quantum confinement limit are emerging as an important class of nanomaterials for novel applications in information technology, optoelectronics, spintronics, and energy storage and conversion technologies. Because of the effects of enhanced quantum confinement and high surface-to-volume ratios, low dimensional materials possess extraordinary chemical and physical properties, including band gaps and metal-semiconductor transitions whose properties can be tuned by altering their doping and layering. As a result, they can range from insulators to topological insulators to semiconductors, and even, superconductors. Understanding the properties of these materials thus presents a materials research opportunity that could have immediate importance to the future design of semiconductor devices. The team aims to develop high accuracy methods to overcome limitations of first principles density-functional-based approaches, particularly in their application to 2D materials, to enable better understanding of experiments. The method development involves combining Quantum Monte Carlo with cluster expansion methods that are commonly used to model alloys. The team will use these methods to study mono/few layer structures of post-transition metal chalcogenides spanning from metals to gap semiconductors. Direct gap compounds for photovoltaics and photoelectrochemical water splitting applications will be designed using alloying as a means to tune phase stability, and electronic and optical properties. The PIs will use this research to educate a diverse body of younger scientists about the physical sciences as part of local outreach efforts to underserved populations, including local high school Girls Who Code Clubs.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.