In QM it's taught that the frequency of a photon emitted when an electron drops from a higher-energy state to a lower-energy state is $\Delta E/h$. In E&M, it's taught that the source of an electromagnetic wave is the acceleration of charge -- and that the frequency of the wave is the same as the frequency of oscillation in the acceleration of charge. Is there a clear explanation of how the electron's motion generates the frequency when an electron drops from one energy state to a lower energy state in an atom? Of course, I realize that the electron is really a wavefunction, not a particle, but still, some component of the electron (or electron wavefunction) must oscillate at the frequency $E/h$ during the transition from the high state to the low state. What is that component?