Spectral densities of strongly correlated electron systems

Peter Fulde

Max Planck Institut für Physik komplexer Systeme, Electronic Correlations, Nöthnitzer Str. 38, 01187 Dresden, Germany

Spectral densities of strongly correlated electron systems can be computes by applying projection techniques when Green's function is calculated. Thereby one identifies in a first step the most important microscopic processes which have to be included for a description of the strong correlations from a physical point of view. Those processes are cast into the form of dynamical variables onto which the memory function is projected. It is demonstrated how this method is applied to Ni, where the satellite 6 eV below the Fermi energy is obtained and to doped Cu-O planes. Here the upper and lower Hubbard bands as well as the Zhang-Rice singlet are reproduced. More recent applications are discussed by Y. Kakehashi.