Supposed external energy is added to the system such that the electron is rise to the next orbital releasing photon. Can QM still be used to model it or does one need Quantum Field Theory? How about additional external energy that increase say the molecular rotational or translational speed, is QM still used here or QFT? If QM is no longer used, does it mean that whenever new external energy is added to the system. QM is no longer valid or do you just add the new energy to the kinetic energy component of the Schroedinger equations??