An in Depth Study of Feshbach Resonance in ⁶Li Collisions

When two slow moving molecules or atoms collide, a repulsive or attractive force occurs that is tunable through an external magnetic field. This physical phenomenon is commonly known as Feshbach resonance (FR). While FR has been observed in many physical systems, the microscopic details of the phenomenon are subtle and it is complicated to find them in the literature. Due to the relevance of FR for cold atoms and the recent efforts to study the phenomenon with molecules, we find it important to investigate FR for two Lithium atoms starting from the fundamental Hamiltonian, including coupling with magnetic fields, relativistic effects and hyperfine coupling. We are confident that our results serve a very important pedagogical purpose, allowing students and researchers to have a deep understanding of the phenomenon. We also present our work in setting up numerical libraries that help us gain further insight and pave the way for future research investigations of molecular systems.