Understanding energy transformation in nanomaterials using absolutely localized electrons

* 人类在本世纪面临的一个重大挑战是从化石燃料过渡到清洁的可再生能源。在全球范围内产生足够量的能量而对环境影响最小的最有前途的方法之一是将太阳能转化为电力和化学燃料。纳米科学提供了一个巨大的潜力，创造更好的材料，为太阳能应用利用新的现象，出现的结构材料单位的大小接近原子尺度。拟议的研究重点是太阳能转化为电力和纳米材料中的化学燃料的基本步骤的第一原理计算研究：电子激发，电荷分离，光致化学反应和电化学过程。它的主要目标是揭示几种知之甚少的微观起源，因此在很大程度上未被利用的纳米级效应，有可能大大推进几种重要的清洁可再生能源技术：* Photophilics：半导体纳米结构中的多激子产生。光催化：在修饰的纳米颗粒上可调地将二氧化碳光还原为燃料，甲醇和甲烷。*电化学：石墨烯和离子液体之间带电界面的高容量储能。为了克服严重限制这些过程的第一原理计算研究的主要障碍，将开发一类新的纳米级模拟电子结构方法。这些方法将利用电子的紧凑局域化表示，以提供优于现有模拟技术的两个关键优势：* 在基态和激发电子态中模拟的前所未有的计算效率，* 对微观现象和纳米材料观察到的性质之间的基本关系的深刻物理见解。拟议的研究不仅将提供许多重要的基本能量转换步骤（例如速率常数，自由能）的可靠定量特征，这可能与纳米材料的关键宏观特性直接相关，而且还将为工程设计用于清洁可再生能源应用的上级设备提出新的创新策略。通过利用量子和统计力学的先进方法，应用数学的现代工具和高性能计算的最新成就，该研究计划是高度跨学科的。其结果将对基础科学（包括化学、物理学、生物学）以及应用工程学科中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.**