Modeling X-ray Transient Spectroscopy with Adaptive Wavefunction Methods

使用自适应波函数方法对 X 射线瞬态光谱进行建模

基本信息

批准号：
1900532
负责人：
Francesco Evangelista
金额：
$ 43.14万
依托单位：
Emory University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-06-01 至 2023-05-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1900532&HistoricalAwards=false
关键词：
Modeling ray Transient Spectroscopy Adaptive

项目摘要

Francesco Evangelista of Emory University is supported by an award from the Chemical Theory, Models and Computational Methods program in the Division of Chemistry to develop computational approaches to study how molecules interact and change in response to exposure to X-ray radiation. X-rays can be used to probe the dynamics of electrons and nuclei during chemical reactions. These experiments have an unprecedented time resolution down to the attosecond scale (one quintillionth of a second). The interpretation of experiments that probe molecules via X-rays relies heavily on quantum mechanical simulations. This involves solving the electronic Schrodinger equation for these systems. Such calculations are challenging due to the combination of relativistic effects and the correlated motion of electrons. Evangelista and his coworkers develop efficient and accurate methods for such simulations. They develop efficient adaptive algorithms that reduce the computational cost of simulating the structure and dynamics of electrons in molecules. They also develop open-source software that implements the theories developed in this project. This software is made available to the broader research community. Evangelista also recruits undergraduates majoring in STEM fields to pursue summer research in his research group. At a fundamental level, the project addresses the problem of computing transient core-excitations with important contributions from both weak and strong correlation. The strategy employed by Evangelista uses compact selected configuration interaction wave functions to describe strong correlation effects and efficient many-body correlation methods to treat weak correlations. The adaptive configuration interaction (ACI) scheme developed in this project is both adaptive and tunable and provides a systematic path to compute excited states with high accuracy. The ACI method is developed to address two challenging problems that require an explicit treatment of highly-excited electronic configurations: the simulation of transient X-ray spectroscopies and the decay of core-ionized and core-excited statesThis 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.

埃默里大学（Emory University）的Francesco福音师得到了化学理论，模型和计算方法计划的奖项，以开发计算方法来研究分子如何相互作用和变化，以响应暴露于X射线辐射。 X射线可用于探测化学反应期间电子和核的动力学。这些实验的时间分辨率一直降低到Attosend量表（一秒钟的千万千分之一）。通过X射线探测分子的实验的解释在很大程度上取决于量子机械模拟。这涉及求解这些系统的电子schrodinger方程。由于相对论效应和电子的相关运动的结合，这种计算具有挑战性。 Evangelista和他的同事为此类模拟开发了有效，准确的方法。他们开发了有效的自适应算法，从而降低了模拟分子中电子结构和动力学的计算成本。他们还开发了实现该项目中开发的理论的开源软件。该软件可用于更广泛的研究社区。 Evangelista还招募了STEM领域主修专业的大学生，以在其研究小组中从事夏季研究。在基本层面上，该项目解决了计算瞬态核心兴趣的问题，并从弱和强相关方面做出了重要贡献。 Evangelista采用的策略使用紧凑的选定配置相互作用波函数来描述强相关效应和有效的多体相关方法来处理弱相关性。在此项目中开发的自适应配置相互作用（ACI）方案既具有自适应又可调，并且提供了一个系统的途径，以高精度计算激发态。开发了ACI方法来解决两个具有挑战性的问题，这些问题需要明确处理高度兴奋的电子配置：瞬态X射线光谱镜的模拟以及核心离子化和核心激发型号的衰落，反映了NSF的宣传任务，反映了NSF的立法任务，并被认为是通过基金会的智力优点和广泛的Crictiation和Broaditia的评估来进行评估，这是值得通过评估的。