The second lecture on excitations in condensed matter will cover electronic excitations in semiconductors and dielectrics, where the electron-hole interaction in the electronically excited state, the exciton, is key. We will explain how the electron-hole interaction arises from Hartree-Fock theory and discuss the limitations of time-dependent density functional theory and Hartree-Fock for the study of excitons. The lecture will then introduce the GW+Bethe-Salpeter method, the standard for studying excitons in condensed matter with an atomistic description.
Jan Wilhelm