Does anyone have a good derivation of the Electron-Phonon Interaction Hamiltonian? I've found a few in various books (specifically B. Ridley and others that cite him) and on the internet, but all of them seem to skip some non-trivial steps or introduce quantities that I've never encountered. On that note, how does one define creation/annihilation operators for phonons? They have no mass (they're not really even particles), so the operators must be different than the standard ones used in the QHO solution. Is the mass the mass of the atoms in the lattice, or maybe some reduced mass?. Thanks.