Understanding energy transformation in nanomaterials using absolutely localized electrons

人类在本世纪面临的一大挑战是从化石燃料向清洁可再生能源的过渡。要在全球范围内以最小的环境影响产生足够的能源，最有希望的方法之一是将太阳光的能量转化为电能和化学燃料。纳米科学提供了巨大的潜力，通过利用随着结构材料单元的大小接近原子尺度而出现的新现象，为太阳能应用创造更好的材料。 这项研究侧重于纳米材料中太阳能转化为电能和化学燃料的基本步骤的第一性原理计算研究：电子激发、电荷分离、光诱导化学反应和电化学过程。它的主要目标是揭示几种鲜为人知的、因此在很大程度上未被利用的纳米级效应的微观起源，这些效应有可能极大地推动几种重要的清洁可再生能源技术： *光伏：在半导体纳米结构中产生多个激子。 *光催化：在修饰的纳米颗粒上，可调谐地将二氧化碳光还原为燃料，即甲醇和甲烷。 *电化学：在石墨烯和离子液体之间的带电界面上进行大容量能量存储。 为了克服严重限制这些过程的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的电子结构方法。这些方法将利用电子的紧凑局域表示来提供与现有模拟技术相比的两个关键优势： **在基态和激发电子态的模拟计算效率前所未有， **对纳米材料的微观现象和观察到的特性之间的基本关系有深刻的物理见解。 这项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)的可靠的量化特征，这些步骤可以直接与纳米材料的关键宏观性质相关，而且还将为设计用于清洁可再生能源应用的优秀设备提供新的创新策略。 通过利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，该研究计划具有高度跨学科的特点。其结果将对包括化学、物理、生物学在内的基础科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.