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Fragment Embedding for Photochemical Electronic Structure Simulations

用于光化学电子结构模拟的片段嵌入

基本信息

批准号：
1900358
负责人：
Troy Van Voorhis
金额：
$ 51万
依托单位：
Massachusetts Institute of Technology
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-06-01 至 2022-05-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1900358&HistoricalAwards=false
关键词：
Fragment Embedding Photochemical Electronic Structure

项目摘要

Professor Troy Van Voorhis of Massachusetts Institute of Technology is supported by an award from the Chemical Theory, Models and Computational Methods Program in the Division of Chemistry. At a microscopic level, chemical reactions determine how long light emitting diodes (LEDs), solar cells, and batteries will last. Recently it has become possible - and even routine - to make predictions about useful lifetimes using computer simulations. These simulations complement experiments by providing insight into properties that might difficult to measure directly. This project considers the use of embedding computer methods that may make it possible to simulate much larger systems with much higher accuracy than ever before. The fundamental idea of embedding involves breaking a large system up into many small, overlapping fragments that can then be stitched back together to describe the whole. The Van Voorhis group uses these embedding tools to study the photochemistry of molecules relevant to emerging organic light emitting device (OLED) and solar cell technologies. Professor Van Voorhis is the departmental coordinator of MIT ACCESS - a joint program between Chemistry, Chemical Engineering and Materials Science that invites a select group of underrepresented minority undergraduate students to visit MIT for a weekend during the academic year. The primary aim is to encourage the students to consider graduate school in chemistry. Professor Van Voorhis also empowers and equips graduate students within his group to introduce K-12 students to the beauty and power of science. Graduate and undergraduate students involved in this award are encouraged to participate in the MIT chemistry "Magic Show" that performs at local schools; the Research Communication Laboratory that trains graduate students to communicate scientific concepts to K-12 students; MIT Women in Chemistry's "Scientist for a Day" middle school camp; and the MIT museum's "Science on Saturdays" program that targets children and families. The Van Voorhis group is developing transformative electronic structure methods in which fragments are the fundamental building blocks. The goal is to create new tools that are both faster and more accurate than state-of-the-art approximations, facilitating chemical simulations that were previously inaccessible. As a starting point, they develop a family of fragment embedding theories based on the Bootstrap Embedding method. The key realization is that wave function embedding allows one to combine overlapping orbital fragments in a robust way. The resulting theory circumvents the scaling challenges inherent in most wave function theories by only requiring calculations on very small fragments, which are ultimately combined to obtain a picture of the entire system. Improvements are accomplished by dressing these embedding methods with dynamic correlation using the many pair expansion (MPE). Finally, these techniques are extended to excited states using a novel strategy that identifies such states as local minima of the energy variance. As a signature application of these tools, the Van Voorhis Group studies the energetics and dynamics of triplet excitons in molecules relevant to emerging OLED and solar cell technologies.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.

麻省理工学院的Troy Van Voorhis教授获得了化学系化学理论、模型和计算方法项目的奖项。在微观层面上，化学反应决定了发光二极管（led）、太阳能电池和电池的使用寿命。最近，利用计算机模拟来预测有效寿命已经成为可能，甚至成为常规。这些模拟通过提供对可能难以直接测量的特性的洞察来补充实验。该项目考虑使用嵌入计算机方法，这可能使模拟比以往更高精度的更大系统成为可能。嵌入的基本思想是将一个大系统分解成许多小的、重叠的片段，然后再拼接在一起来描述整个系统。Van Voorhis团队使用这些嵌入工具来研究与新兴有机发光器件（OLED）和太阳能电池技术相关的分子光化学。Van Voorhis教授是麻省理工学院ACCESS项目的部门协调员，该项目是化学、化学工程和材料科学之间的一个联合项目，邀请一组被忽视的少数民族本科生在学年期间访问麻省理工学院度过一个周末。主要目的是鼓励学生考虑在化学专业读研。Van Voorhis教授还授权和装备他小组内的研究生，向K-12学生介绍科学的美丽和力量。参与该奖项的研究生和本科生被鼓励参加麻省理工学院化学“魔术表演”，在当地学校表演；培养研究生向K-12学生传达科学概念的研究传播实验室；麻省理工学院女性化学协会的“一天科学家”中学夏令营；以及麻省理工学院博物馆针对儿童和家庭的“周六科学”项目。Van Voorhis小组正在开发变革性的电子结构方法，其中碎片是基本的构建块。目标是创造比最先进的近似更快、更准确的新工具，促进以前无法实现的化学模拟。在此基础上，他们发展了一系列基于自举嵌入方法的片段嵌入理论。关键的实现是波函数嵌入允许以稳健的方式组合重叠的轨道碎片。由此产生的理论绕过了大多数波函数理论固有的尺度挑战，只需要对非常小的片段进行计算，这些片段最终结合起来获得整个系统的图像。利用多对展开（MPE）对这些嵌入方法进行动态关联处理，从而实现了改进。最后，使用一种新的策略将这些技术扩展到激发态，该策略将这些状态识别为能量方差的局部最小值。作为这些工具的一个标志性应用，Van Voorhis小组研究了与新兴OLED和太阳能电池技术相关的分子中的三重态激子的能量学和动力学。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。