Many-Body Diagrammatic Expansion in a Kohn-Sham Basis: Implications for Time-Dependent Density Functional Theory of Excited States

I. V. Tokatly; O. Pankratov

doi:10.1103/PhysRevLett.86.2078

Many-Body Diagrammatic Expansion in a Kohn-Sham Basis: Implications for Time-Dependent Density Functional Theory of Excited States

I. V. Tokatly and O. Pankratov

Phys. Rev. Lett. 86, 2078 – Published 5 March 2001

Abstract

We formulate diagrammatic rules for many-body perturbation theory which uses Kohn-Sham Green's functions as basic propagators. The diagram technique allows one to study the properties of the dynamic nonlocal exchange-correlation (xc) kernel $f_{xc}$ . We show that the spatial nonlocality of $f_{xc}$ is strongly frequency dependent. In particular, in extended systems the nonlocality range diverges at the excitation energies. This divergency is related to the discontinuity of the xc potential.