Advances in computing charge carrier dynamics in oxides from first principles

Advances in first-principles calculations enable accurate predictions of charge carrier mobility and scattering mechanisms in materials. However, many oxides remain an open problem for these methods since they exhibit soft phonon modes due to structural phase transitions and electron-phonon interactions strong enough to form polarons. The presence of polarons and soft modes makes first-principles calculations of charge transport highly challenging even in non-correlated oxides.
This talk will discuss new approaches for treating electron-phonon coupling due to soft phonon modes, as well as a cumulant diagram-resummation approach for rigorously computing the carrier mobility in the large polaron regime. We apply these approaches to cubic SrTiO3 perovskite as a paradigmatic case and analyze in detail soft mode and polaron contributions to charge transport.
Our advances allow us to accurately predict the temperature dependence [1] and absolute value [2] of the mobility in SrTiO₃, while providing long-sought microscopic details about the scattering mechanisms, bandstructure renormalization and beyond-quasiparticle features in the spectral function due to the strong electron-phonon coupling. Efforts to extend these calculations to a range of oxides and future application of these approaches to interfaces and heterostructures will be discussed

[1] J.-J. Zhou, O. Hellman, M. Bernardi. “Electron-Phonon Scattering in the Presence of Soft Modes and Electron Mobility in SrTiO3 Perovskite from First Principles.” Phys. Rev. Lett. 121, 226603 (2018)
[2] J.-J. Zhou, M. Bernardi. "Predicting Charge Transport in the Presence of Polarons: The Beyond-Quasiparticle Regime in SrTiO3." Preprint: Arxiv 1905.03414.