XXXVI. Self energy of slow electrons in polar materials

Abstract

Summary A new variational method is developed to treat the properties of slow electrons in ionic crystals, and similar problems. It is shown that the true energy of the ground state is always lower than the energy obtained from second order perturbation theory, however strong the interaction. The corresponding wave functions differ, however, from those of perturbation theory unless the interaction is sufficiently weak. For NaCl the energy of the ground state is found lower than by any previous method, and hence closer to the true energy. The effective mass is of the order of twice the electronic mass; no trapping takes place, therefore.