This talk presents a fully relativistic density functional method (named quasi-four-component algorithm, Q4C) under the framework of numeric atom-centered orbitals (NAOs). Q4C initially projects the atomic solution to (electron-only) positive-energy states and eventually deals with only two components but retains the full precision of traditional four-component relativistic methods. While Q4C inherently reduces the dimension of the Hamiltonian matrix and the corresponding computational demand in diagonalization, the adoption of localized NAO basis functions in solids further reduces the computational demand in real space operations, enabling us to investigate large and complex systems containing heavy elements fully relativistically. As benchmarks, the relativistic band structures of 103 common materials are reported. I will also demonstrate the applicability of the massively parallel method to complex hybrid organic-inorganic (HOIP) perovskites containing Pb and Bi 

Rundong Zhao obtained his B.S. in Applied Physics from Shandong University in 2010, and his PhD in Physical Chemistry from Peking University in 2015. He then visited Beijing Computational Science Research Center from 2015 to 2016 and moved to Hong Kong Baptist University as a postdoctoral research fellow from 2016 to 2018. He is a postdoctoral associate at Duke University since Feb. 2018. His research interest is electronic structure theory, including both method/code development and application in bulk systems and surface science. He is the author of BDF-PBC (an DFT code for relativistic effects calculations in periodic systems) and a core developer of the FHI-aims electronic structure code. With the exact two-component (X2C) and quasi-four-component (Q4C) method implemented by him, FHI-aims is currently the first fully relativistic code that can work for large periodic systems (with hundreds of atoms in a unit cell) containing heavy elements, in which the SOC effect is significant but was not treated exactly. These systems involve: perovskites, topological insulators, etc.