We are interested in electron and energy flow through complex molecular systems. We develop excited-state (stochastic) electronic structure theory (many-body perturbation theory, e.g. GW, Bethe-Salpeter equation) and nonadiabatic (quantum) dynamics (beyond Born-Oppenheimer approximation, e.g. surface hopping, electronic friction) to describe electron transfer, energy relaxation, exciton recombination, light-matter interactions, and coherence control in complex chemical systems, e.g. inside an optical cavity, within nanomaterials, and at molecule-metal interfaces.