RUI: Development of Computational Methods and Applications to Molecules in Microsolvation Environments.

RUI：微溶剂化环境中分子的计算方法和应用的开发。

• 批准号: 1565495
• 负责人: Thomas Sommerfeld
• 金额: $ 10.18万
• 依托单位: Southeastern Louisiana University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1565495&HistoricalAwards=false
• 关键词: RUI; Development; Computational; Methods; Applications

Thomas Sommerfeld of Southeastern Louisiana University is supported by an award from the Chemical Theory, Models and Computational Method program in the Chemistry Division and the NSF EPSCoR office to investigate how extra electrons aid in breaking chemical bonds. Chemical bonds themselves are electrons shared between atoms and can be thought of as a glue holding the atoms in a molecule together. The electron-glue analogy, however, only goes so far, because a bond can be weakened by both too little and too much glue, and weak bonds can be cleaved during the permanent motion of the atoms. In other words, adding an electron to a molecule generally weakens its bonds, and the resulting so-called temporary anion may undergo either bond cleavage or, alternatively, reemit the extra electron. Concrete examples where this reaction is applied or happens naturally are: plasma chemistry and plasma etching, chemistry in the ionosphere, damage to living tissue by ionizing radiation, cancer therapy with electron beams, and reduction reactions with solvated electrons, the so-called Birch reduction. This research project supports the development of computer models of the temporary anion, the first intermediate formed in these electron-induced reactions. This research is carried out with collaborators and with undergraduate researchers. In order to introduce undergraduates to this research, Dr. Sommerfeld also designs educational mini-projects, which are only indirectly related to the current main project, but can be addressed with 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, simply, resonances. On the one hand, he develops ab initio methods to characterize resonances, and on the other hand he applies the newly developed methods in selected applications. Computing both the energy and finite lifetime of a resonance is still a notoriously challenging task for quantum chemistry, because it combines an electron-scattering with an electron-correlation problem. To address the continuum aspect, Dr. Sommerfeld either uses complex-absorbing-potentials or the analytic-continuation-in-the-coupling-constant method. To address the correlation aspect, he uses the symmetry-adapted-cluster configuration-interaction method, an electronic structure method closely related to the equation-of-motion coupled-cluster method. One particular point of emphasis is the artificial stabilizing potential added to the Hamiltonian in the analytic-continuation-in-the-coupling-constant method. Dr. Sommerfeld aims to identify a short-range stabilizing potential that improves the subsequent analytic-continuation step. On the application side Dr. Sommerfeld's goals are to examine resonance states, which differ in electronic structure from a closed-shell neutral either by one-hole (Auger-like resonances) or by one excitation (e.g. Penning ionization or resonant photodetachment). For these resonances, treating electron correlation in a balanced way is particularly challenging. Dr. Sommerfeld studies temporary anion resonances embedded in small molecule clusters with the goal of identifying trends in the change of the resonance parameters associated with the interaction strength (permanent dipole, higher order multipoles, dispersion) of the embedding molecules.

路易斯安那大学东南大学的托马斯·索默菲尔德（Thomas Sommerfeld）得到了化学理论，模型和计算方法计划的奖项，并在化学部和NSF EPSCOR办公室获得了研究，以研究额外的电子如何帮助破坏化学债券。化学键本身是原子之间共有的电子，可以被认为是将原子固定在一起的胶。然而，电子胶水类比只能到目前为止，因为粘结可以被太少和太多的胶水削弱，并且在原子的永久运动过程中可以裂解弱键。换句话说，将电子添加到一个分子中通常会削弱其键，而所得的所谓临时阴离子可能会进行键裂解，或者，或者，或者，恢复多余的电子。混凝土示例是在自然应用或自然发生的那样：血浆化学和等离子体蚀刻，电离层中的化学，通过电离辐射，对电子束的癌症治疗，电子束对活组织的损害以及与溶剂化电子的还原反应，所谓的Birch减少。 该研究项目支持临时阴离子的计算机模型的开发，这是这些电子诱导反应中的第一个中间体。 这项研究是与合作者和本科研究人员一起进行的。 为了向本研究介绍本科生，Sommerfeld博士还设计了教育迷你项目，这仅与当前的主要项目间接相关，但可以使用标准的量子化学方法来解决，以便可以逐步介绍他的学生。在这个项目中，索默菲尔德博士研究了电子亚稳态的状态 - 所谓的共振状态或简单地共鸣。一方面，他开发了从头算方法来表征共振，另一方面，他在选定的应用程序中应用了新开发的方法。计算共振的能量和有限寿命仍然是量子化学的挑战性的一项挑战，因为它将电子散发的结合与电子相关问题相结合。为了解决连续体方面，Sommerfeld博士要么使用复杂的吸收潜力或在耦合组合方法中进行分析。 为了解决相关方面，他使用了对称适应的群集配置相互作用方法，这是一种与动作方程耦合群集方法密切相关的电子结构方法。重点的一个特殊点是在耦合 - 恒定方法中添加了哈密顿量的人工稳定潜力。 Sommerfeld博士旨在确定短期稳定潜力，以改善随后的分析范围步骤。在应用方面，Sommerfeld博士的目标是检查共振状态，这些共振状态在电子结构上与封闭壳中性不同（通过单孔样共振）或一种激发（例如，笔球电离或共振光检查）。对于这些共鸣，以平衡的方式处理电子相关性特别具有挑战性。 Sommerfeld博士研究嵌入在小分子簇中的临时阴离子共振，目的是识别与嵌入分子的相互作用强度（永久性偶极，高阶，分散体）相关的谐振参数变化的趋势。