Understanding energy transformation in nanomaterials using absolutely localized electrons

***本世纪人类面临的主要挑战是从化石燃料向清洁的可再生能源过渡。在全球范围内以最小的环境影响产生足够能量的最有希望的方法之一是将太阳能转化为电能和化学燃料。纳米科学通过利用结构材料单元接近原子尺度时出现的新现象，为创造更好的太阳能应用材料提供了巨大的潜力。***拟开展纳米材料中太阳能转化为电能和化学燃料基本步骤的第一性原理计算研究：电子激发、电荷分离、光致化学反应和电化学过程。它的主要目的是揭示一些鲜为人知的微观起源，因此在很大程度上尚未开发的纳米尺度效应有可能极大地推进几个重要的清洁可再生能源技术：****光伏：半导体纳米结构中的多激子产生。****光催化：可调的光还原二氧化碳燃料，甲醇和甲烷，在装饰纳米颗粒。****电化学：石墨烯和离子液体之间带电界面的高容量能量存储。为了克服严重限制这些过程第一性原理计算研究的主要障碍，将开发一类用于纳米级模拟的新型电子结构方法。这些方法将利用电子的紧凑局域表示，与现有的模拟技术相比，提供两个关键优势：*****在基态和激发态中模拟的前所未有的计算效率，*****对微观现象和观察到的纳米材料性质之间的基本关系的深刻物理见解。***所提出的研究不仅将提供许多重要的基本能量转换步骤（如速率常数，自由能）的可靠定量特征，这些特征可以直接关系到纳米材料的关键宏观性质，而且还将为清洁可再生能源应用的工程高级设备提供新的创新策略。***本研究项目采用量子力学和统计力学的先进方法、现代应用数学工具和高性能计算的最新成果，是一个高度跨学科的研究项目。其结果将对基础科学（包括化学、物理、生物学以及应用工程学科）的材料计算设计产生重大影响

***A major challenge facing mankind in this century is the transition from fossil fuels to clean renewable energy sources. One of the most promising approaches to generate sufficient amount of energy on a global scale with minimal environmental impact is to convert the energy of sunlight into electricity and chemical fuels. Nanoscience offers an enormous potential for creating better materials for solar applications by taking advantage of new phenomena, which emerge as the size of structural material units approach the atomic scale.***The proposed research focuses on first-principle computational studies of basic steps of the conversion of solar energy into electricity and chemical fuels in nanomaterials: electron excitations, charge separation, photoinduced chemical reactions, and electrochemical processes. Its main objective is to reveal microscopic origins of several poorly understood and thus largely unexploited nanoscale effects that have a potential to greatly advance several important clean renewable energy technologies:**** Photovoltaics: multiple exciton generation in semiconductor nanostructures.**** Photocatalysis: tunable photoreduction of carbon dioxide to fuels, methanol and methane, on decorated nanoparticles.**** Electrochemistry: high-capacity energy storage at the charged interface between graphene and ionic liquids.***To overcome major obstacles that have severely limited first-principle computational studies of these processes a new class of electronic structure methods for nanoscale simulations will be developed. These methods will exploit a compact localized representation of electrons to provide two key advantages over the existing simulation techniques:***** an unprecedented computational efficiency of simulations in the ground and excited electronic states,***** a deep physical insight into fundamental relations between microscopic phenomena and observed properties of nanomaterials.***The proposed research will not only provide reliable quantitative characteristics of many important elementary energy conversion steps (e.g. rate constants, free energies), which can be directly related to key macroscopic properties of nanomaterials, but will also suggest new innovative strategies for engineering superior devices for clean renewable energy applications.***By utilizing advanced methods of quantum and statistical mechanics, modern tools of applied mathematics and recent achievements in high-performance computing, the research program is highly interdisciplinary. Its results will have a significant impact on computational design of materials in fundamental science including chemistry, physics, biology as well as in applied engineering disciplines.**