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) 项目以及刺激竞争性研究既定项目 (EPSCoR) 的支持下，南卡罗来纳大学的 Sophya Garashchuk 教授将开发结合分子和材料中原子核的量子行为的理论和计算方法。本研究旨在通过第一性原理建模和理论分析，在时间和空间上跨越多个数量级，深入了解分子组装体和纳米材料的特性及其与光、电流和热的相互作用。开发的方法将应用于实验系统，有助于阐明化学反应性以及电荷和能量转移的内在机制，并预测此类过程的速率。对系统特性和对温度、电场和磁场等外部刺激的响应进行建模，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再到量子技术的广泛应用。加拉什丘克教授的研究和教育活动将为新兴量子信息科学和技术劳动力的发展做出贡献。她将在她所在的大学以及南卡罗来纳州主要本科院校的学生和科学家中积极推广计算化学工具的教育和研究。 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对研究的参与，并向南卡罗来纳州的广大公众传播 STEM（科学、技术、工程和数学）成就，南卡罗来纳州是一个在全球研究企业中地理代表性不足的州。根据该奖项开发的理论框架将包括对轻核（例如质子）的量子力学描述，轻核在水溶液以及生物和纳米设备环境中无处不在。由于数值成本呈指数缩放，这种严格的处理仅适用于少数原子核，并且它将保留用于化学活性轻的原子核。这种级别的描述将与由于小幅度核运动和结构重排而影响能量和电荷流的较大分子环境的经典表示相结合。这种分层方法将基于针对全量子核的演化波函数而定制的时间相关高斯基，与重核的简化量子（例如解冻高斯）描述集成，与动态电子结构评估兼容，并将扩展到电子非绝热过程。加拉什丘克还将开发基于概率密度连续性的核子空间分解电子核动力学。这种形式主义将用于针对涉及通过核运动和外部场耦合的大量电子态的分子动力学，例如分子/纳米粒子系统。在教育和更广泛的影响领域，加拉什丘克将培训理论、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.