Datensatz

Zusammenfassung

First-principle approaches for phonon-limited electronic transport are typically based on many-body perturbation theory and transport equations. With that, they rely on the validity of the quasi-particle picture for electrons and-phonons, which is known to fail in strongly anharmonic systems. In this work, we demonstrated the relevance of effects beyond the quasi-particle picture by combining ab initio molecular dynamics and the Kubo-Greenwood (KG) formalism to establish a non-perturbative, stochastic method to calculate carrier mobilities while accounting for all orders of anharmonic and electron-vibrational couplings. In particular, we propose and exploit several numerical strategies that overcome the notoriously slow convergence of the KG formalism for both-electronic and nuclear degree of freedom in crystalline solids. The capability of this method is demonstrated by calculating the temperature-dependent electron mobility of the strongly anharmonic oxide perovskites SrTiO₃ and BaTiO₃ across a wide range of temperatures. We show that the temperature-dependence of the mobility is largely driven by anharmonic, higher-order coupling effects and rationalize these trends in terms of the non-perturbative electronic spectral functions.