Density Functional Theory (DFT) has firmly established itself as the
workhorse for atomic-level simulations of condensed phases, pure or
composite materials and quantum chemical systems. This work offers a
rigorous and detailed introduction to the foundations of this theory, up
to and including such advanced topics as orbital-dependent functionals
as well as both time-dependent and relativistic DFT. Given the many
ramifications of contemporary DFT, the text concentrates on the
self-contained presentation of the basics of the most widely used DFT
variants: this implies a thorough discussion of the corresponding
existence theorems and effective single particle equations, as well as
of key approximations utilized in implementations. The formal results
are complemented by selected quantitative results, which primarily aim
at illustrating the strengths and weaknesses of particular approaches or
functionals. The structure and content of this book allow a tutorial and
modular self-study approach: the reader will find that all concepts of
many-body theory which are indispensable for the discussion of DFT -
such as the single-particle Green's function or response functions - are
introduced step by step, along with the actual DFT material. The same
applies to basic notions of solid state theory, such as the Fermi
surface of inhomogeneous, interacting systems. In fact, even the
language of second quantization is introduced systematically in an
Appendix for readers without formal training in many-body theory.
