Modeling X-ray Transient Spectroscopies with Advanced Multireference Methods

使用先进的多参考方法对 X 射线瞬态光谱进行建模

• 批准号: 2312105
• 负责人: Francesco Evangelista
• 金额: $ 50.17万
• 依托单位: Emory University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-06-01 至 2026-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2312105&HistoricalAwards=false
• 关键词: Modeling; ray; Transient; Spectroscopies; Advanced

With support from the Chemical Theory, Models and Computational Methods (CTMC) program in the Division of Chemistry, Francesco Evangelista of Emory University is developing computational approaches to simulate highly reactive molecules interacting with X-ray radiation. New experimental techniques use X-rays to track the dynamics of electrons and nuclei during chemical reactions at extremely short time scales. These experiments can also reveal how molecules interact with their environment. It is difficult to extract the atomistic mechanism of reactions from X-ray experiments alone. Quantum mechanical calculations play an important role in interpreting X-ray experiments. Scientists cannot accurately perform these calculations for many interesting molecules due to the challenges created by the correlated motion of electrons. Evangelista and his research group are developing methods that will enable simulations of state-of-the-art experiments that can be used to track reactions in complex chemical environments. This project will create new open-source computer codes that implement the theories developed by Evangelista and that are freely available. The Evangelista group also plans to engage undergraduates in summer research as part of the team to help build the future STEM (science, technology, engineering and mathematics) workforce.Under this award, Francesco Evangelista and his team will develop methods to compute core-excited states for molecules in regimes where many-body correlations contribute significantly to the wave function. The approach will employ the driven similarity renormalization group (DSRG) formalism to account for dynamical correlation effects to produce an effective Hamiltonian for a manifold of electronic states. The project seeks to develop a new technique to target specific valence- and core-excited diabatic states and will apply these methods to simulate state-of-the-art experiments that track bond-dissociation processes. The group also seeks to extend their computations to molecules adsorbed on semiconductors and solid-state defect qubits by combining the GAS (general activation space)-DSRG approach with multi-reference quantum embedding methods. These techniques are intended to address the problem of computing full X-ray absorption spectra for transient species as their molecular geometry and electronic state evolve over time. The proposed methods will be general in that they will apply to both ground and valence-excited starting states. More broadly, these developments are expected contribute to the advancement of multi-reference theories with potential impact on the related areas of photochemistry and chemical reactivity. These methods are potentially deployable for the simulation of diamond defects with relevance to quantum information science (QIS) as, for example, in the use of X-ray spectroscopy for the characterization of solid-state qubits.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.

在化学理论的支持下，模型和计算方法（CTMC）在化学划分中计划，埃默里大学的Francesco福音派正在开发计算方法，以模拟与X射线辐射相互作用的高反应性分子。新的实验技术使用X射线在非常短的时间尺度下化学反应期间在化学反应过程中跟踪电子和核的动力学。这些实验还可以揭示分子如何与环境相互作用。仅凭X射线实验提取反应的原子机制很难。量子机械计算在解释X射线实验中起重要作用。由于电子相关运动所带来的挑战，科学家无法准确地对许多有趣的分子进行这些计算。 Evangelista及其研究小组正在开发方法，这些方法将启用最新的实验模拟，这些实验可用于跟踪复杂化学环境中的反应。该项目将创建新的开源计算机代码，以实现Evangelista开发的理论，并且可以自由使用。 Evangelista集团还计划在夏季研究中吸引本科生，作为团队的一部分，以帮助建立未来的STEM（科学，技术，工程和数学）劳动力。该方法将采用驱动的相似性重归其化组（DSRG）形式主义来解释动态相关效应，从而为电子状态的流形产生有效的哈密顿量。该项目旨在开发一种针对特定价值和核心兴奋的绝症状态的新技术，并将应用这些方法模拟跟踪键 - 分解过程的最新实验。该小组还试图通过将气体（一般激活空间）-DSRG方法与多参考量子嵌入方法相结合，将其计算扩展到吸附在半导体和固态缺陷量值上的分子。这些技术旨在解决瞬态物种计算全X射线吸收光谱的问题，因为它们的分子几何形状和电子状态会随着时间的流逝而发展。所提出的方法将是普遍的，因为它们将适用于地面和价值兴奋的起始状态。更广泛地说，这些发展有助于多参考理论的发展，并可能影响光化学和化学反应性的相关领域。这些方法可能可用于模拟与量子信息科学（QIS）相关的钻石缺陷，例如，在使用X射线光谱法来表征固态码头的表征中。该奖项反映了NSF的法定任务，并认为通过基金会的知识优点和广泛的criperia criperia criperia criperia criperia criperia criperia criperia criperia criperia criperia criperia criperia criperia criperia criperia均值得通过评估。