Quantum Dynamics with Nuclear Quantum Effects: a Hhierarchical Methodology for Large Molecular Systems

在化学系化学理论，模型和计算方法（CTMC）计划以及刺激竞争性研究的既定计划（EPSCoR）的支持下，南卡罗来纳州大学的Sophya Garashchuk教授将开发理论和计算方法，将分子和材料中原子核的量子行为结合起来。本研究旨在通过第一性原理建模和理论分析，深入了解分子组装体和纳米材料的性质及其与光，电流和热的相互作用，跨越时间和空间的几个数量级。开发的方法将被应用到实验系统，有助于阐明化学反应性和电荷和能量转移的内在机制，并预测这些过程的速率。模拟系统特性和对外部刺激（如温度、电场和磁场）的响应将指导实验，加速新材料和分子器件的开发，用于从燃料电池到催化剂再到量子技术的广泛应用。Garashchuk教授的研究和教育活动将有助于新兴量子信息科学和技术工作队伍的发展。她将在她的大学和南卡罗来纳州主要的本科院校的学生和科学家中积极推广教育和研究中的计算化学工具。 她的研究小组将参加K-12科学演示和科学展示，突出化学在前沿科学进步和日常技术中的作用。这些活动将扩大代表性不足的群体在研究和传播STEM方面的参与（科学、技术、工程和数学）成就向南卡罗来纳州的公众展示，这个州在全球研究企业中的地理代表性不足。在这个奖项下正在开发的理论框架将包括轻核的量子力学描述，如质子，普遍存在于水溶液以及生物和纳米器件环境中。由于数值成本的指数缩放，这种严格的处理仅适用于少数核，并且将保留用于化学活性轻核。这一水平的描述将合并与影响能量和电荷流由于小幅度核运动和结构重排的较大分子环境的经典表示。这种分层方法将基于与时间相关的高斯基，该高斯基适合于全量子核的演化波函数，并与简化的量子（e. G.解冻高斯）描述的重核，兼容的飞行电子结构评估，并将扩展到电子非绝热过程。Garashchuk还将开发基于概率密度连续性的核子子空间因子化电子核动力学。这种形式主义将被用于目标分子动力学，涉及大量的电子状态耦合通过核运动和外部领域，例如分子/纳米粒子系统。在教育和更广泛的影响领域，Garashchuk将培训理论、计算化学和高性能计算方面的初级研究人员;她将通过正式的教学和合作项目促进实验同事使用计算化学工具。该奖项反映了NSF的法定使命，并通过使用基金会的智力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 support from the Chemical Theory, Models and Computational Methods (CTMC) program in the Division of Chemistry, and the Established Program to Stimulate Competitive Research (EPSCoR), Professor Sophya Garashchuk of the University of South Carolina will develop theoretical and computational methods incorporating the quantum behavior of the nuclei within molecules and materials. This research aims to gain in-depth understanding of the properties of molecular assemblies and nanomaterials and their interactions with light, electric current and heat through the first-principles modeling and theoretical analysis, spanning several orders of magnitude in time and space. The developed methodology will be applied to experimental systems, helping to elucidate the intrinsic mechanisms of chemical reactivity and charge and energy transfer, and to predict the rates of such processes. Modeling system properties and responses to external stimuli, such as temperature, electric and magnetic fields, will guide experiment, accelerating the development of new materials and molecular devices for wide-range applications from fuel cells to catalysis, to quantum technologies. Professor Garashchuk's research and educational activities will contribute to the development of the emerging quantum information science and technology work force. She will actively promote computational chemistry tools in education and research among students and scientists at her university and at predominantly undergraduate institutions in the state of South Carolina. Her research group will participate in K-12 science demonstrations and science showcases highlighting the role of chemistry in the forefront scientific advances and in everyday technologies. These activities will broaden participation of the underrepresented groups in research and communicate STEM (science, technology, engineering and mathematics) achievements to the general public of South Carolina, a state geographically underrepresented in the global research enterprise.The theoretical framework being developed under this award will include a quantum mechanical description of light nuclei, such as protons, ubiquitous in aqueous solutions and biological and nanodevice environments. Because of the exponential scaling of the numerical cost, this rigorous treatment is feasible for just a few nuclei, and it will be reserved for the chemically active light nuclei. This level of description will be merged with the classical representations of the larger molecular environment affecting the energy and charge flow due to small amplitude nuclear motion and structural rearrangements. This hierarchical approach will be based on the time-dependent Gaussian bases tailored to an evolving wavefunction for the fully quantum nuclei, integrated with a simplified quantum (e. g. thawed Gaussian) description of the heavy nuclei, compatible with on-the-fly electronic structure evaluation, and will be extended to electronically nonadiabatic processes. Garashchuk will also develop nuclear-subspace factorized electron-nuclear dynamics based on probability density continuity. This formalism will be used to target molecular dynamics involving a large number of electronic states coupled through nuclear motion and external fields, e.g. molecule/nanoparticle systems. In the area of education and broader impacts, Garashchuk will train junior researchers in theoretical, computational chemistry, and high-performance computing; she will facilitate use of computational chemistry tools by experimental colleagues through formal teaching and collaborative projects.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.