On the density of states for the Hubbard model: pseudo-particle Keldysh diagram method - an alternative to DMFT?
P. I. Arseyev, N. S. Maslova+
Lebedev Physical Institute of the RAS, 119991 Moscow, Russia
+Department of Physics, Lomonosov MSU, 119992 Moscow, Russia
Abstract
It is shown how to construct Keldysh diagram technique for pseudo-particle
approach to the Hubbard model.
We propose self consistent equations for
pseudo particle and electron Green functions in Keldysh diagram technique.
Nonlocal effects (spatial dispersion) are included in single impurity problem
in this method.
Thus we can get rid of the artificial central peak (of Kondo type) in the
density of states which is
inevitable in Dynamical Mean Field Theory (DMFT).
The changes in the density of states for 2D Hubbard model
due to variation of Coulomb repulsion U and electron
concentration are analyzed.