TTEP: A code for efficient calculation of the thermal transport from constant electron-phonon coupling approximation

A Fortran code named TTEP (Thermal Transport from constant Electron-Phonon coupling approximation) is presented in this work. Within the framework of firstprinciples calculation, this code utilizes the deformation potential approximation to replace the electron-phonon (EP) coupling matrix element in the phonon scattering due to EP interaction. By adopting this approximation, our method achieves a balance between computational efficiency and accuracy, enabling the exploration of the thermal transport from EP interaction with much reduced computational consumption. One of the key features of TTEP is its versatility in handling a broad range of carrier concentration, including both hole and electron doping. We also extend the applicability of TTEP to actual doping case and capture EP effect over a wide temperature range. Other scattering mechanisms, such as grain boundary scattering and phonon-phonon interaction, have been included in the calculation of lattice thermal conductivity through the Matthiessen's rule. Several test cases are presented in this work to demonstrate the above features.