Theoretical Chemistry of Unbound Electrons

ended

T-CUBE aims at the theoretical modeling of chemistry involving the continuum. Traditionally, chemistry has been concerned with electrons that remain bound to the nuclei during a reaction. However, in many settings that deal with X rays or plasma, electrons can enter and leave the system; they are unbound. Most theoretical approaches for unbound electrons are not applicable to extended systems in complex environments. As a consequence, pathways and product distributions of processes such as dissociative electron attachment and Coulomb explosion are poorly understood. This hinders progress in laboratory and technology: The electron is a simple and versatile catalyst, but corresponding applications are still in an infant stadium. T-CUBE seeks to overcome these limitations. Often, unbound electrons can be described by resonances, electronic states with complex-valued energy. In recent years, I contributed to advancing this approach significantly. Small molecules in gas phase can now be described with an accuracy that allows for quantitative comparison to experiment. Here, I propose to investigate the chemistry of unbound electrons in larger molecules and condensed phase, for example, in solutions, polymeric networks, and biomolecules. Aspects that we will address include: energetics and character of resonances in different environments, resulting changes in chemical reactivity, and the interplay of nuclear motion and electron loss. To achieve these goals, quantum chemistry for electronic resonances needs to be advanced substantially. We will develop electronic-structure methods suitable for over a hundred of atoms, a quantum embedding scheme for describing different environments, and molecular dynamics simulations that take into account electron loss. In addition, we will advance the theory of electronic resonances itself. In exemplary applications, we will investigate phenomena involving dissociative electron attachment, electron transfer, and Coulomb explosion.