CAREER: Theoretical Investigation of Photo-induced Charge and Energy Transfer in Organic Photovoltaic Materials

康奈尔大学的Nandini Ananth得到了化学系化学理论、模型和计算方法计划颁发的职业奖的支持，该计划旨在开发新的理论方法，以揭示推动材料系统中有效的电子和能量传输的因素的详细、原子水平的图景。化学作用与光和热等外力的微妙平衡决定了复杂分子系统中反应的结果。目前的研究重点是设计能够吸收太阳光子并高效产生自由电子的有机太阳能电池材料。这项研究的长期目标是开发一套完整的理论方法工具箱，为与可再生能源技术相关的材料提供通用的、可移植的设计原则。使用数学工具了解化学反应是拟议工作的核心，并反映在该奖项的教育宣传部分。早期融入数学对教育后期的科学能力有很大影响，是鼓励人们参与科学、技术、工程和数学(STEM)事业的重要一步。这一挑战是通过与高需求学区合作制定课程计划和演示来解决的，这些课程计划和示范鼓励将数学工具逐步纳入科学课堂。这项工作涉及的技术挑战包括准确地模拟大型多原子系统的电子结构，以及开发一种计算高效的方法来将量子动力学效应纳入凝聚相电荷和能量转移过程。电子结构的挑战是用基于片段的方法来解决的，其中一个大的系统计算被分成许多使用高水平理论的较小子系统的精确计算。动力学的挑战是开发一种能够准确捕捉量子效应的方法，但这是基于经典分子动力学的，在经典分子动力学中，计算工作量与系统大小成正比。这里，这是通过将复杂系统的量子动力学映射到使用量子力学的路径积分表示导出的同构经典系统的经典动力学来实现的。这里开发的方法是通用的，并允许准确地研究复杂系统中的量子行为，应用于凝聚相光化学以外的许多领域。该组织与纽约州的学校，特别是锡拉丘兹市高需求重点地区的学校合作，开发包含数学内容的课程和材料，并满足州政府通过的新的下一代科学标准。

Nandini Ananth of Cornell University is supported by a CAREER award from the Chemical Theory, Models and Computational Methods program in the Chemistry Division to develop new theoretical methods to uncover a detailed, atomistic-level picture of the factors that drive efficient electron and energy transport in material systems. A delicate balance of chemical interactions along with external forces like light and heat determine the outcomes of reactions in complex molecular systems. The current research focuses on designing organic solar cell materials that absorb solar photons and efficiently generate free electrons. The long-term objectives of this research are to develop a complete toolbox of theoretical methods that can provide general, transferable design principles for materials relevant to renewable energy technology. The use of mathematical tools to understand chemical reactions is central to the proposed work, and is reflected in the educational outreach component of this award. The early incorporation of mathematics significantly impacts aptitude for science in the later stages of education and is an important step towards encouraging participation in Science, Technology, Engineering and Mathematics (STEM) careers. This challenge is addressed by working with high-need school districts to develop lesson plans and demonstrations that encourage the gradual incorporation of mathematical tools in science classrooms. The technical challenges addressed in this work include accurately modeling the electronic structure of large, many-atom systems and developing a computationally efficient method to incorporate quantum dynamic effects in condensed-phase charge and energy transfer processes. The electronic structure challenge is addressed with fragment-based methods where a large system calculation is divided into many accurate calculations on smaller subsystems using a high level of theory. The challenge of dynamics is to develop a method that can accurately capture quantum effects, but that is based on classical molecular dynamics where the computational effort scales well with system size. Here, this is achieved by mapping the quantum dynamics of a complex system to the classical dynamics of an isomorphic classical system derived using the path-integral representation of quantum mechanics. The methods developed here are general, and allow accurate studies of quantum behavior in complex systems with applications to many areas beyond condensed-phase photochemistry. The group works with schools in New York State, and in particular the high-needs focus district of Syracuse City, to develop curricularmaterials that incorporate math and that meet the new Next Generation Science Standards adopted by the state.