Density-functional theory of one-electron propagators

Swapan K. Ghosh

Marat Valiev, Gayanath Fernando

We present a rigorous formulation of generalized Kohn-Sham density-functional theory. This provides a straightforward Kohn-Sham description of many-body systems based not only on particle-density but also on any other observable. We illustrate the formalism for the case of a particle-density based description of a nonrelativistic many-electron system. We obtain a simple diagrammatic expansion of the exchange-correlation functional in terms of Kohn-Sham single-particle orbitals and energies; develop systematic Kohn-Sham formulation for one-electron propagators and many-body excitation energies. This work is ideally suited for practical applications and provides a rigorous basis for a systematic development of the existing body of first-principles calculations in a controllable fashion.

Eugene S. Kryachko, Eduardo V. Ludeña

Marat Valiev

First principles calculations of many-body systems represent an important tool for investigating the properties of real materials. This work describes the effective action formalism as a rigorous theoretical framework for the development for such calculations. Similar to density-functional theory the effective action formalism reduces the analysis of an interacting many-body system to a self-consistent solution of single-particle equations. This formalism is free of the limitations of the conventional density-functional theory. It is equally applicable for the analysis of ground as well as excited state properties. The formalism is illustrated by constructing density and spin-density based description of nonrelativistic many-electron system. This leads to an explicit diagrammatic expressions for the exchange-correlation functional and provides a systematic density based analysis of one-electron propagators and many-body excitation energies. Numerical results for the excitation energies for several closed shell atoms are presented. ^

ROBERT K. NESBET

Many theoretical methods for N -electron systems use a reference state whose electronic density in general differs from that of the associated eigenstate. In contrast, the density functional theory of Kohn and Sham postulates a model reference system for which these two densities are identical. An alternative postulate, requiring the reference state to have maximum projection on the true wave function (the Brueckner−Brenig construction), is shown here to provide a theory in which the ground-state energy is a functional of the reference-state density. This revised formalism makes it possible to identify elements of the theory with specific formulas and concepts of formal many-body theory. In particular, the one-electron wave functions are in one-to-one correspondence with physical quasiparticles of a generalized Fermi-liquid theory, and the one-electron energies are Landau quasiparticle energies.

Francesc Malet, André Mirtschink, Klaas J. H. Giesbertz +1 more