Two-particle excitations of the Hubbard Hamiltonian: alloy analogy solution

Abstract

The spectra of the two-hole and the two-electron excitations are calculated for a single-band Hubbard Hamiltonian. Equations of motion for retarded two-particle double-time Green function are solved using a decoupling based on the alloy analogy. The solution is correct in exactly solvable limiting cases and has also correct behaviour in the regime of the strong electron-electron correlations.