CAREER: Developing Low-Cost Computational Models for the Photoexcited Dynamics of Noble Metal Nanoclusters

凭借这个职业奖，布兰迪斯大学的Rebecca Gieseking得到了化学系化学理论，模型和计算方法项目的支持，以开发计算模型来了解光与金属纳米团簇的相互作用。金属纳米团簇有可能通过利用光产生化学燃料来彻底改变太阳能技术，因为它们支持等离子体，等离子体是电子的集体振荡，使纳米团簇能够强烈吸收光。理解、控制和操纵等离子体特性是提高太阳能存储效率的关键。Gieseking博士和她的研究小组正在开发计算成本低的精确模型，以了解金属纳米团簇吸收光后的衰变过程。他们正在使用这些模型来了解这些衰变过程如何随着纳米团簇的大小，形状和成分而变化，以设计具有可控衰变时间尺度的金属纳米团簇，以实现高效的太阳能存储。Gieseking博士还在整个化学课程中开发新的计算化学实验室练习，以向本科生介绍该领域并加深他们对重要化学性质的理解。除了她的研究贡献，Gieseking博士通过招募研究生，通过ChemWMN指导，（化学妇女指导网络），Rebecca Gieseking博士和她的研究小组正在开发基于半绝热分子动力学（NAMD）模型的非绝热分子动力学（NAMD）模型，经验方法来理解金属纳米团簇（NC）的光激发动力学。原子精确的贵金属NC是强吸收体，其可以通过改变NC尺寸和形状来调节，并且激发态动力学从激子（指示离散激发态）到等离子体激元（反映近连续的状态）变化。Gieseking博士正在对半经验量子力学（SEQM）方法进行参数化，以准确地再现Ag和Au NC的激发态势能表面，并利用NAMD代码进行动力学的表面跳跃模拟。该项目旨在通过以下方式推进等离子体增强热电子化学的知识状态：（i）为贵金属NCs的原子激发态动力学提供一种新的低成本计算模型;（ii）揭示影响激发态动力学的结构-性质关系，可用于定制NCs，以应用于太阳能和其他太阳能技术。这些方法旨在提供从激子到等离子体行为的转变的基本见解，并通过使用动力学来完善等离子体的现有量子力学定义。如果成功的话，这些研究将朝着使用SEQM方法利用等离子体激元热电子进行工业重要反应的愿景迈出重要的一步。该奖项反映了NSF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。

With this CAREER award, Rebecca Gieseking of Brandeis University is supported from the Chemical Theory, Models and Computational Methods program in the Division of Chemistry to develop computational models to understand the interactions of light with metal nanoclusters. Metal nanoclusters have the potential to revolutionize solar energy technologies by harnessing light to produce chemical fuels because they support plasmons, which are collective oscillations of the electrons that enable the nanoclusters to strongly absorb light. Understanding, controlling, and manipulating the plasmon properties is key to improving the efficiency of solar energy storage. Dr. Gieseking and her research group are developing accurate models with low computational costs to understand the decay processes after metal nanoclusters absorb light. They are using these models to understand how these decay processes change as a function of nanocluster size, shape, and composition to design metal nanoclusters with controllable decay time scales for efficient solar energy storage. Dr. Gieseking is also developing new computational chemistry laboratory exercises throughout the chemistry curriculum to introduce undergraduates to the field and deepen their understanding of important chemical properties. Beyond her research contribution, Dr. Gieseking is engaged in promoting the participation of women and underrepresented minorities in chemistry through recruiting research students, mentoring through ChemWMN (Chemistry Women Mentoring Network), and participating in Brandeis’s outreach to local schools.Dr. Rebecca Gieseking and her research group are developing nonadiabatic molecular dynamics (NAMD) models based on semi-empirical methods to understand the photoexcited dynamics of metal nanoclusters (NCs). Atomically precise noble metal NCs are strong absorbers that can be tuned by changing the NC size and shape, and the excited-state dynamics vary from excitonic (indicating discrete excited states) to plasmonic (reflecting a near-continuum of states). Dr. Gieseking is parametrizing semi-empirical quantum mechanical (SEQM) methods in an effort to accurately reproduce the excited-state potential energy surfaces of Ag and Au NCs and utilizing NAMD codes for surface-hopping simulations of the dynamics. This project aims to advance the state of knowledge in plasmon-enhanced hot-electron chemistry by (i) providing a novel low-cost computational model for the atomistic excited-state dynamics of noble metal NCs and (ii) revealing structure-property relationships that affect the excited-state dynamics, which can be used to tailor NCs for applications in photocatalysis and other solar energy technologies. These methods aim to provide fundamental insight into the transition from excitonic to plasmonic behavior and refine existing quantum mechanical definitions of plasmons by using dynamics. If successful, these studies will make important strides toward the vision of using SEQM methods to harness plasmonic hot electrons for photocatalysis of industrially important reactions.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.