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

在化学系化学理论、模型和计算方法项目的支持下，东南部路易斯安那大学的托马斯·索默菲尔德教授将对临时分子阴离子进行建模。通过自发电子发射而衰变的带负电荷的分子离子被称为临时阴离子，因为它们的寿命与其他物种相似。暂时的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存在，包括等离子体刻蚀、大气化学、对生物组织的辐射损伤和癌症治疗。对临时阴离子进行建模比对稳定分子进行建模更具挑战性。索默菲尔德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的量子力学方程，包括发出的电子。Sommerfeld教授将致力于开发可靠、经济高效的模型来计算临时阴离子的寿命，这是进行更粗粒度模拟的关键参数。此外，索默菲尔德博士的团队将应用开发的方法来帮助解释印第安纳大学奇克·贾罗尔德博士的团队测量的光分离光谱。由于东南大学是一所位于传统低收入州的农村低收入地区的PUI(以本科生为主的机构)，而且由于研究将与本科生小组成员一起进行，因此对弱势学生及其使用研究基础设施的影响预计将是显著的。在该奖项下，托马斯·萨默菲尔德教授和他的小组将把共振态的方法开发与光分离实验的研究结合起来。Sommerfeld博士将把他的系统方法比较框架从模型势扩展到电子结构世界，并从L？方法扩展到投影算符方法。共振的方法至少包括五个方面：连续体方法、电子结构方法、价基、扩散基和数据分析。由于这些计算涉及大量因素，比较具有挑战性，Sommerfeld博士将重点放在连续统方法的无偏见比较上。为此，Sommerfeld博士将在开源PSI4包中实现对称性一致的限制势。Sommerfeld博士将使用新的和传统的方法来帮助解释光脱离光谱，通过阐明初始状态分布，识别短暂的中间体，并提出机制。Sommerfeld小组的这些研究有可能产生广泛的科学影响；最重要的是，在PSI4中开发用于比较连续统方法和基于限制势的方法的系统框架将有利于临时阴离子电子结构领域的研究界。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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 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.