QClub seminar: Lukas Muechler

Abstract: In this talk, we propose a topological classification of molecules and their chemical reactions with and without many-body interactions. We consider molecular Hamiltonians in a real-space tight-binding basis with time-reversal symmetry and an additional spatial reflection symmetry. On a single particle level, the reflection symmetry gives rise to a perplectic structure which can be probed by a Wilson loop using a flux-insertion. The classification in terms of Wilson loops remains stable in the presence of many-body interactions, which can be explained by the presence of zeros of the interacting single particle Green’s function.

We argue that this topological classification possesses a universal contribution to the rate constants of chemical reactions due to the breakdown of the Born-Oppenheimer approximation. Our theory is applied to a class of chemical reactions studied by Woodward and Hoffmann, where a reflection symmetry is preserved along a one-dimensional reaction path.