Fighting Complexity with Simplicity - Models, Theoretical Tools, and Numerical Techniques in Modern Molecular Physics

Abstract

The studies I present in this thesis cover a wide range of physical phenomena: high-harmonic generation, photoelectron and electronic circular dichroism, quantum resonances in molecular scattering at low temperatures, and photoassociation of molecular dimers at high temperatures. The theoretical investigation of the corresponding physics required a similarly broad arsenal of tools and techniques: frame transformations, the time-independent and time-dependent Schrödinger equation, the density matrix formalism and the Lindblad master equation, toy model potentials, specifically crafted measures, and vibrationally-averaged transition dipole moments just to name a few. The overarching philosophy of the research presented is that in order to understand the essence of quantum physical phenomena in molecular experiments, a deliberate focus on simplicity in models and techniques can unlock an intuitive understanding unobscured by needless complexity. Although in some cases the simplicity of the modelling comes at the prize of a fully quantitative agreement, it still allows to capture the most important qualitative aspects of the underlying physics to guide our theoretical understanding and inspire future experimental design.