Electron–Phonon Interaction as Effective Electron–Electron Interaction

Abstract

AbstractAfter rederiving the tight‐binding electron–phonon Hamiltonian for a diatomic chain with special emphasis on the dispersion of the coupling constant the linear electron–phonon interaction is transformed into an effective Electron–Electron one following Chatterjee and Mitra (CM). The subsequent Hartree‐Fock decoupling with inclusion of anomalous averages allows for a simple treatment. Within the one‐mode approximation (keeping q = 0‐phonons only), Bogolyubov's method of approximating Hamiltonian leads to the mean‐field result, therefore, CM's “opposite Born‐Oppenheimer approximation” cuts off the kinetic phonon energy.