摘要：

First principles approaches for the phonon-limited electronic transport are typically based on many-body perturbation theory and the Boltzmann transport equations. These methods approximate atomic vibrations as harmonic and rely on the validity of the quasiparticle picture for electrons and phonons. However, they are known to break down in strongly anharmonic systems, where the atomic vibrations become highly complex and irregular. In this work, we go beyond the quasiparticle picture and the harmonic approximation by combining ab initio molecular dynamics and the Kubo-Greenwood (KG) formalism to develop a non-perturbative, stochastic method for calculating carrier mobilities. To address the notoriously slow convergence of the KG formalism in crystalline solids, we employ several numerical strategies in all-electron, numeric atom-centered orbital basis ab inito simulation package FHI-aims to enhance computational efficiency. The capability of KG formalism is then demonstrated by calculating the temperature-dependent electron mobility of the strongly anharmonic oxide perovskites SrTiO3 and BaTiO3 across a broad temperature range.

Furthermore, to gain deeper insight into the underlying physics, we introduce a fully anharmonic, non-perturbative electronic spectral function. To achieve this, we developed an efficient and accurate band unfolding approach for non-orthogonal linear combination of atomic orbitals (LCAO) basis sets. Based on group-theoretical analysis, we derive analytical expressions for the primitive cell translational operator in the supercell AO basis. Our implementation in FHI-aims enables large-scale, all-electron band unfolding calculations for systems with thousands of atomsl.

报告人简介：

Jingkai Quan is currently pursuing his PhD at the Fritz Haber Institute of the Max Planck Society (FHI) and the Max Planck Institute for the Structure and Dynamics of Matter (MPSD), under the supervision of Prof. Matthias Scheffler and Prof. Angel Rubio. He received his B.S. in Materials Physics from Jilin University in 2020, under the supervision of Prof. Lijun Zhang. His PhD research focuses on density functional theory code development, electronic transport theory, and light–matter interaction. He is an active developer of the all-electron ab initio materials simulation package FHI-aims.

邀请人：任新国（82649603）