Analytic treatment of Mott-Hubbard transition in the half-filled Hubbard model and its thermodynamics

The Mott-Hubbard transition in the half-filled Hubbard model is studied analytically on a Bethe lattice for the paramagnetic state and the classical N\'eel state. The single-particle density of states is obtained by calculating the one-particle Green's function represented by the Lanczos infinite continued fraction. The paramagnetic solution shows that the Mott-Hubbard transition is signaled by both collapsing Hubbard bands at Uc=2t* and a sharp Lorentzian peak appearing at midgap at UUc. For the N\'eel state, however, the system becomes an insulator for U>0. We also obtain the specific heat and entropy for both the metallic and insulating regimes. Our analytic work reproduces the key results obtained by numerical method in infinite dimensions.