%0 Journal Article
%T Ab-initio theory of superconductivity - I: Density functional formalism and approximate functionals
%A M. L¨ąders
%A M. A. L. Marques
%A N. N. Lathiotakis
%A A. Floris
%A G. Profeta
%A L. Fast
%A A. Continenza
%A S. Massidda
%A E. K. U. Gross
%J Physics
%D 2004
%I arXiv
%R 10.1103/PhysRevB.72.024545
%X A novel approach to the description of superconductors in thermal equilibrium is developed within a formally exact density-functional framework. The theory is formulated in terms of three ``densities'': the ordinary electron density, the superconducting order parameter, and the diagonal of the nuclear N-body density matrix. The electron density and the order parameter are determined by Kohn-Sham equations that resemble the Bogoliubov-de Gennes equations. The nuclear density matrix follows from a Schroedinger equation with an effective N-body interaction. These equations are coupled to each other via exchange-correlation potentials which are universal functionals of the three densities. Approximations of these exchange-correlation functionals are derived using the diagrammatic techniques of many-body perturbation theory. The bare Coulomb repulsion between the electrons and the electron-phonon interaction enter this perturbative treatment on the same footing. In this way, a truly ab-initio description is achieved which does not contain any empirical parameters.
%U http://arxiv.org/abs/cond-mat/0408685v2