[GS_C_MS] Beyond-quasiparticles spectral functions and transport from electron-phonon coupling
ABSTRACT
We develop a many-body framework for first-principles calculations of electron spectral functions and transport due to electron-phonon interactions. We introduce a nonperturbative, self-consistent method for spectral functions [1], which accurately captures the broadening and satellite features beyond the Dyson-Migdal and cumulant approaches. Building on this spectral function, we then solve the ladder equations that describe phonon-limited transport with both beyond-quasiparticle effects and vertex corrections [2]. This approach unifies and improves upon the two state-of-the-art methods, the Boltzmann transport equation and the bubble approximation. We validate the developed methods against numerically exact results for model Hamiltonians and apply them to study the spectral functions, DC conductivity, and optical properties of real semiconductors and metals.
[1] Jae-Mo Lihm and Samuel Ponce, Phys. Rev. Lett. 134, 186401 (2025)
[2] Jae-Mo Lihm and Samuel Ponce, in preparation.