RUI: Computational Methods for Molecular Resonances and Study of Electron-induced Reactions

东南路易斯安那大学的Thomas Sommerfeld教授得到了化学系化学理论、模型和计算方法项目的支持。他开发了计算方法来研究被称为分子阴离子的负电荷分子的性质。额外电子(负电荷)的存在会改变分子中化学键的强度。当附近的原子共享电子时，就形成了化学键。这些共享的电子就像一种“胶水”，将原子聚集在一起形成一个分子。然而，胶水太少或太多都会削弱化学键。如果键足够弱，分子阴离子就会变得亚稳，键很容易被打破。或者，亚稳态的分子阴离子可以进行重排并释放一个电子，这样它就可以恢复到更强、更稳定的键。这些现象的应用领域包括集成电路的蚀刻，涉及高层大气中的化学反应的研究，对生物组织的辐射损伤，以及一些癌症治疗。Sommerfeld博士开发了亚稳态阴离子的计算机模型。制作亚稳态阴离子分子的计算机模型是一个挑战，因为人们需要模拟描述亚稳态阴离子中所有电子的量子力学运动方程，以及由释放的电子产生的所有可能的重排物种的所有电子。索默菲尔德博士的目标是找到一种可靠、经济高效的方法来计算电子释放所需的时间，电子释放是表征亚稳态阴离子的关键参数。该项目是在东南路易斯安那大学进行的，这是一所以本科为主的大学。Sommerfeld教授让低收入和代表性不足的学生参与研究项目，这些项目涉及高水平的理论和复杂的计算方法。为了让本科生了解这项研究，他还用标准的量子化学方法设计了教育微型项目，让他的学生一步步地被介绍到研究领域。在这个项目中，索默菲尔德博士研究了电子亚稳态，也就是所谓的共振态。他发展了表征共振的第一性原理方法，并用这些方法研究电子诱导的反应。计算共振的能量和寿命对量子化学来说是一项具有挑战性的任务，因为它结合了电子散射现象和电子关联问题。Sommerfeld博士追求的目标是提高用于计算共振能量的现有方法之一的准确性和可靠性，他还致力于更具体的项目，旨在系统地实施一套可靠的方法。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。

Professor Thomas Sommerfeld of Southeastern Louisiana University is supported by an award from the Chemical Theory, Models and Computational Methods program in the Division of Chemistry. He develops computational methods to study the properties of negatively charged molecules called molecular anions. The presence of extra electrons (negative charges) can alter the strengths of the chemical bonds in a molecule. A chemical bond is formed when electrons are shared between nearby atoms. These shared electrons act like a "glue" that hold the atoms together to form a molecule. However, the presence of either too little or too much glue can weaken a chemical bond. If the bond is weakened enough, a molecular anion can become metastable and the bond can be easily broken. Alternatively, the metastable molecular anion can undergo a rearrangement and release an electron so that it can go back to having stronger, more stable bonds. Examples of areas in which these phenomena are applied are the etching of integrated circuits, studies involving chemical reactions in the upper atmosphere, radiation damage to living tissue, and some cancer therapies. Dr. Sommerfeld develops computer models of metastable anions. Making computer models of metastable anionic molecules is a challenge because one needs to simulate the quantum mechanical equations of motion describing all the electrons in the metastable anion, as well as all the electrons of all possible rearranged species that result from the released electron. Dr. Sommerfeld's goal is to identify a reliable, cost-efficient method to calculate the time it takes for electron release, a critical parameter for characterizing metastable anions. The project is being carried out at Southeastern Louisiana University, a predominantly undergraduate institution. Professor Sommerfeld engages lower income and underrepresented students in research projects involving high-level theory and sophisticated computational methods. In order to introduce undergraduates to this research, he also designs educational mini-projects using standard quantum chemistry methods,so that his students can be introduced to the research area step-by-step. In this project Dr. Sommerfeld studies electronically metastable states, so called resonance states, or resonances. He develops first-principles methods that characterize resonances and employs these methods to study electron-induced reactions. Computing both the energy and lifetime of a resonance is a challenging task for quantum chemistry because it combines an electron-scattering phenomenon with an electron-correlation problem. Dr. Sommerfeld pursues objectives that aim at improving the accuracy and reliability of one of the existing methods used to compute the energy of resonances and he pursues more specific projects aimed at implementing a set of reliable methods in systematic steps.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.