Self-consistent theory of electron correlation in the Hubbard model

The Dyson equation for the two-time thermal Green's functions is used for a self-consistent calculation of the single-particle Green's functions in the Hubbard model. The method makes it possible to obtain a generalized interpolation solution of the Hubbard model valid for arbitrary relationship between the effective band width and the Coulomb repulsion parameter. Two variants of the theory make it possible to obtain two exact representations for the mass operator, which are used to obtain approximate solutions in the atomic and band limits.