Correlations and Density Functional Theory

The Density Functional Theory (DFT) and its extensions to time-dependent systems and to special types of ground states is formulated, as a powerful framework to perform explicit and accurate calculations for atoms, molecules, crystals and nanosystems and obtain good agreement in comparison with experimental findings. Concepts, methods, and applications are illustrated. The discussion around the DFT represents a framework where many puzzle pieces found in previous Chapters fit together: the approach adopted within approximate models such Thomas- Fermi and Hartree and Hartree-Fock methods, the density and current-density response theories used to understand the transport in Chap. 4 and optical in Chap. 5 behaviors, the crystal, electron and phonon structures investigated in Chaps. 1, 2 and 3.