Finite-temperature numerical renormalization group study of the Mott transition

Wilson's numerical renormalization group method for the calculation of dynamic proper-ties of impurity models is generalized to investigate the effective impurity model of the dynamical mean-field theory at finite temperatures. We calculate the spectral function and self-energy for the Hubbard model on a Bethe lattice with infinite coordination number directly on the real-frequency axis and investigate the phase diagram for the Mott-Hubbard metal-insulator transition. While for T<T-c<approximate to>0.02W (W: bandwidth) we find hysteresis with first-order transitions both at U-c1 (defining the insulator to metal transition) and at U-c2 (defining the metal to insulator transition), at T>T-c there is a smooth crossover from metalliclike to insulatinglike solutions.