Intramolecular quantum dynamics on intersecting potential energy surfaces: a tutorial review

Vibronic coupling-i.e. the interaction between molecular electronic states through the nuclear motion - is an ubiquitous phenomenon for molecular electronic spectra and dynamics in excited electronic states. While the Born-Oppenheimer or adiabatic separation of electronic and nuclear motions remains the cornerstone of our thinking in the field, the ensuing limitations are often thought of almost in line with the theorem itself. In this short review paper, we attempt to give a lucid overview over some basics in the field complemented by relevant examples. While written from a personal perspective, it is nevertheless hoped to provide some useful insight for the beginner and expert alike.