Contribution of long-wavelength transverse optical phonons to electron-phonon coupling in doped polar insulators

We estimate the contribution of the long-wavelength el-TO-ph interaction and discuss the effect it has on electron-phonon scatterings in doped polar systems like SrTiO3 and PbTe. The analytical and numerical results presented in the study indicate that the el-TO-ph interaction tends to contribute little to the total strength of electron-phonon coupling in these and related materials. To explain this fact we consider possible reasons why the effect of the polar long-wavelength transverse optical phonons on the coupling constant λ is far less than one might suppose.