Influence of the temperature and the dielectric characteristics of a medium on the properties of a polaron

The Feynman method extended to nonvanishing temperatures is used to investigate the influence of the temperature and the dielectric absorption profile of a medium on the properties (energy, mobility) of an electron in a polar dielectric linear medium. It is shown that in the strong coupling limit the energy is independent of the temperature and depends only on the static and optical permittivity of the medium, whereas in the case of weak coupling (weakly polar medium) the dependence on the temperature and the profile of the dielectric absorption spectrum becomes important. Calculations are made of the mobility for media with a strong low-frequency absorption.