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

该奖项支持以促进对二维材料的理解为重点的理论和计算研究。二维(2D)材料具有非凡的性能。它们是迄今发现的最坚固的材料之一，可以从金属转变为半导体，反之亦然，只需将它们层层堆叠、拉伸或掺杂即可。这表明2D材料在储能、电池和半导体器件方面具有潜在的应用前景。研究小组将使用称为量子蒙特卡罗方法的高精度模拟技术，来阐明有趣的无机2D材料、过渡金属二卤化物和过渡后金属硫化物的性质。基于已发现的材料特性，该团队的目标是设计并模拟新的2D材料，这些材料适用于性能优于传统设备的电子设备，并利用光来分解水分子以获取氢气以获取能源。该奖项还支持该团队通过大学申请和年度科学博览会进程指导服务不足的地区学生的努力，以及教育不同的年轻科学家关于物理科学的团体，这是当地向服务不足的人群，包括当地高中编程女孩俱乐部扩展努力的一部分。技术总结该奖项支持以促进对二维材料的理解为重点的理论和计算研究。量子受限范围内的二维(2D)无机材料是一类重要的纳米材料，在信息技术、光电子学、自旋电子学、能量存储和转换技术等领域具有重要的应用前景。由于增强的量子限制和高比表面积比的影响，低维材料具有特殊的化学和物理性质，包括带隙和金属-半导体跃迁，这些性质可以通过改变它们的掺杂和分层来调节。因此，它们的范围从绝缘体到拓扑绝缘体，再到半导体，甚至超导体。因此，了解这些材料的性质提供了一个材料研究的机会，可能对未来半导体器件的设计具有直接重要的意义。该团队的目标是开发高精度的方法，以克服第一原理基于密度泛函的方法的局限性，特别是在将其应用于2D材料方面，以使更好地理解实验。该方法的发展包括将量子蒙特卡罗方法与通常用于模拟合金的团簇展开方法相结合。该团队将使用这些方法来研究从金属到GaP半导体的过渡后金属硫化物的单层/少数层结构。用于光伏和光电化学分水应用的直接带隙化合物将被设计为使用合金化作为调整相稳定性以及电子和光学性能的手段。PIS将利用这项研究教育不同的年轻科学家关于物理学的知识，作为当地向服务不足的人群的推广努力的一部分，包括当地的高中女孩谁编程俱乐部。这一奖项反映了NSF的法定使命，并已被认为值得支持，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。

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.