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

Southeastern Louisiana University, Hammond LA

Investigators

Abstract

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.