Density Functional Theory of Super-Phenomena in Condensed Systems

Abstract

Density functional theory (DFT) is considered as the standard model for low/very low energy physics. The theory appeared with its full glory when Hohenberg and Kohn [1] proved that the ground state properties of an interacting many body system can be described by a functional of the one-particle density of the system. The theory has a rigorous formal structure with a well-defined energy functional. Unfortunately the theorem does not tell how to construct the functional, hence the functional remains unknown in the exact sense. In view of the complexity of problems of a many-body nature, it is expected to make explicit construction of the functional by suitable approximations.