β Scribed by Richard M. Martin; Gerardo Ortiz
No coin nor oath required. For personal study only.
Density functional theory DFR rests upon the proofs by Hohenberg and Kohn, which show that all properties of quantum many-body systems are functionals of the ground-state density, and the KohnαSham construction, in which the exchangeαcorrelation energy is a functional only of the density. DFT has been widely assumed to apply directly to the intrinsic bulk properties of extended systems such as crystals, e.g., the static dielectric properties of insulators. However, in 1995, Godby, Ghosez, and Godby pointed out that the assumptions of DFT do not strictly apply to the case of a crystal in a finite electric field, since there is no ground state, and they argued that the description of intrinsic bulk dielectric phenomena in a crystal requires a functional of both the bulk density and the polarization. Here, we discuss the results of Ε½ . recent work which show that in the limit of long wavelengths both the bulk periodic density and the bulk average macroscopic polarization are necessary to fully describe the dielectric properties of insulating materials.
π SIMILAR VOLUMES
This paper discusses the properties of an interacting condensed Bose system, emphasizing those aspects which do not depend on the weakness of the potential, and which therefore apply to superfluid helium. A physical and mathematical characterization of Bose condensation is presented in terms of an a