DFT Kohn-Sham formalism and Exchange correlation functionals

This lecture covers the Density Functional Theory (DFT) Kohn-Sham formalism introduced in 1965, explaining the re-introduction of wavefunctions for an auxiliary noninteracting reference system with the same density. It delves into the Kohn-Sham energy functional, the Kohn-Sham equations, and the types of exchange-correlation functionals, including Local Density Approximation (LDA) and Generalized Gradient Approximations (GGAs). The lecture also discusses the performance of LDA in approximating nonuniform systems and the determination of parameters for GGAs.