RUI: Characterizing Valence, Temporary, and Non-valence Anions: Computational Methods and Photo-detachment Spectroscopy

在化学系的化学理论、模型和计算方法项目的支持下，东南路易斯安那大学的托马斯索末菲教授将模拟暂时的分子阴离子。通过自发电子发射衰变的带负电荷的分子离子被称为暂时阴离子，因为它们显示出与其他物种相似的寿命。暂时性阴离子不能形成稳定的化合物，但它们在许多自然和技术过程中作为关键中间体出现，包括等离子体蚀刻，大气化学，对活组织的辐射损伤和癌症治疗。模拟临时阴离子远比模拟稳定分子更具挑战性。Sommerfeld博士和他的团队的目标是模拟描述临时阴离子的所有电子（包括传出电子）的量子力学方程。Sommerfeld教授将致力于开发可靠的，具有成本效益的模型来计算临时阴离子的寿命，这是更粗粒度模拟的关键参数。此外，Sommerfeld博士的小组将应用开发的方法来帮助解释印第安纳州大学Chick Jarrold博士的小组测量的光分离光谱。因为东南是一个PUI（主要是本科院校）位于传统上低收入国家的农村低收入地区，由于研究将与本科生群体成员一起进行，预计对弱势学生及其获得研究基础设施的影响将是显著的。根据该奖项，托马斯·索末菲教授和他的小组将把共振态的联合收割机方法发展与光分离实验的研究结合起来。Sommerfeld博士将扩展他的系统方法比较框架，从模型势到电子结构世界，从L ²方法到投影算子方法。共振的方法结合至少五个方面：连续方法，电子结构方法，价基，扩散基础和数据分析。由于大量的因素进入这些计算，比较是具有挑战性的，索末菲博士将专注于连续体方法的无偏比较。为此，Sommerfeld博士将在开源Psi4软件包中实现符合标准的限制电位。Sommerfeld博士将使用新的和传统的方法来帮助解释光剥离光谱，阐明初始状态分布，识别短暂的中间体，并提出机制。索末菲小组的这些研究具有广泛的科学影响力;最重要的是，发展一个系统的框架来比较Psi4中的连续介质方法和基于约束势的方法，将有利于临时阴离子电子结构领域的研究团体。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识产权进行评估来支持。优点和更广泛的影响审查标准。

With support from the Chemical Theory, Models and Computational Methods program in the Division of Chemistry, Professor Thomas Sommerfeld of Southeastern Louisiana University will model temporary molecular anions. Negatively charged molecular ions that decay by spontaneous electron emission are called temporary anions as they show lifetimes similar to other species. Temporary anions cannot form stable compounds, but they occur as critical intermediates in many natural and technical processes including plasma etching, atmospheric chemistry, radiation damage to living tissue, and cancer therapy. Modeling temporary anions is far more challenging than modeling of stable molecules. Dr. Sommerfeld and his group aim to simulate the quantum mechanical equations describing all electrons of the temporary anion including the outgoing electron. Professor Sommerfeld will work to develop reliable, cost-efficient models to compute the lifetime of temporary anions, a critical parameter for more coarse-grained simulations. Moreover, Dr. Sommerfeld’s group will apply the developed methods to aid with the interpretation of photo-detachment spectra measured by Dr. Chick Jarrold’s group at Indiana University. Since Southeastern is a PUI (predominantly undergraduate institution) located in a rural, low-income region of a traditionally low-income state, and since the research will be conducted with undergraduate group members, the impact on disadvantaged students and their access to the research infrastructure is expected to be significant.Under this award, Professor Thomas Sommerfeld and his group will combine method development for resonance states with the study of photo-detachment experiments. Dr. Sommerfeld will extend his framework for systematic method comparison from model potentials into the electronic structure world and from L²-methods to projection-operator approaches. Methods for resonances combine at least five aspects: a continuum approach, an electronic structure method, a valence basis, a diffuse basis, and a data analysis. Owing to the large number of factors entering these calculations, comparisons are challenging, and Dr. Sommerfeld will focus on an unbiased comparison of continuum methods. For this purpose, Dr. Sommerfeld will implement symmetry-conforming confinement potentials into the open-source Psi4 package. Dr. Sommerfeld will use the new and traditional methods to aid in the interpretation of photo-detachment spectra by elucidating initial state distributions, identifying short-lived intermediates, and suggesting mechanisms. These studies from the Sommerfeld group have the potential for broad scientific impact; most importantly, the development of a systematic framework for comparing continuum methods and the confinement potential based methods in Psi4 would be beneficial for the research community in the area of temporary anion electronic structure.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.