Calculation of electron-phonon interaction strength from first principles in graphene and silicon

The calculation of electron-phonon interaction from first principles has recently become feasible using density-functional perturbation theory (Quantum Espresso) [1] and the small displacement method (GPAW) [2]. We determine the strength of the electron-phonon interaction using the Vienna Ab-Initio Simulation Program (VASP) [3] with the small displacement method using PHONOPY [4]. We illustrate our approach using graphene and calculate the interband deformation potentials for bulk Si relevant for Band-to-Band Tunneling (BTBT).