專題演講

2020/12/17(Thu)     11:00 -12:00    五樓第一會議室5th Floor(1st meeting room)

Title

Applications of density functional theory: from single-particle picture to many-body physics

Speaker

Dr. Chi-Cheng Lee

Department of Physics, Tamkang University

Abstract

First-principles calculations based on density functional theory have been widely performed to understand and predict abundant physical properties of condensed matter. In this talk, the basic idea of density functional theory will be first introduced for highlighting three important ingredients: Kohn-Sham orbitals, the many-body charge density, and the many-body total energy. I will then discuss two issues based on the studies of Kohn-Sham orbitals, namely, the discovery of Weyl fermions in TaAs and the emergence of nearly flat bands in the two-dimensional Ge layer on ZrB2(0001). For the many-body charge density, the surface-assisted orbital order in CeCoIn5 will been discussed. Finally, I will address the absolute values of core-level binding energy for several materials, where the many-body total energies are needed to reproduce the experimentally observed XPS spectra.