Influence of the Electron‐Phonon Coupling on Energy States of Wannier Excitons

Theen ergies of Wannier excitons are investigated taking into account the electron‐phonon coupling described by the Fröhlich‐type interaction. The energies of the ground and the first excited states are calculated by a variational treatment. The exciton is treated as an interacting polaron pair, the electron‐phonon coupling of which is mutually disturbed. The expansion in terms of the particle momenta reproduces in the first order the effective potential derived by Haken. The following terms can be interpreted as additional mass renormalizations depending on the exciton radius. These terms are found to improve the agreement with experiment.