  The ability to calculate the electron-phonon coupling (e-ph) from first
principles is of tremendous interest in materials science, as it provides a
non-empirical approach to understand and predict a wide range of phenomena.
While this has largely been accomplished in the Kohn-Sham framework of density
functional theory (KS-DFT), it is becoming more apparent that standard
approximations in KS-DFT can be inaccurate. These discrepancies are often
attributed to a non-local potential where more advanced approaches to DFT or
many-body perturbation theory have been used. However, a highly reliable and
efficient first-principles approach to compute these quantities is still
missing. With the goal of realizing a high-fidelity description of e-ph, we
present a new field-theoretical methodology, incorporating the seminal work of
Baym and Hedin within the quasiparticle self-consistent GW (QSGW)
approximation, and the Questaal electronic structure package.
