Translational Motion of a Free Large Polaron and Broadening of Absorption Spectra (Report‪)‬

1. Introduction ITS is well known that the absorption spectra of free large polaron consists of a broad featureless asymmetric band with a long tail extended to the short-wave length region. There is vast literature on the possible mechanisms of broadening the optical spectrum of free polaron. S. I. Pekar [1] have studied the broadening of the optical absorption spectra of large polaron in crystal as a function of phonon dispersion. In the work [2] authors have calculated the optical absorption coefficient for free polarons using the multiphonons mechanism. The main idea in ref. [3] consist that broadening of the absorption spectra depends on width of an electronic band. In this case broadening of the absorption spectra to proportionally electron effective mass at the bottom of a conductivity band [4]. However the question of a contribution to the broadening from the translational degrees of freedom and from the corresponding velocities is still unanswered. In this work the thermal motion of free quasiparticle as a whole is analyzed in the context of its effect on the broadening of the optical absorption spectra.