On the analyticity of solutions in the dynamical mean-field theory

The unphysical solutions of the periodic Anderson model obtained by Keiter and Leuders (Keiter H and Leuders T 2000 Europhys. Lett. 49 801) in dynamical mean-field theory (DMFT) are shown to result from the authors' restricted choice of the functional form of the solution, leading to a violation of the analytic properties of the exact solution. By contrast, iterative solutions of the self-consistency condition within the DMFT obtained by techniques which preserve the correct analytic properties of the exact solution (e.g., quantum Monte Carlo simulations and the numerical renormalization group technique) always lead to physical solutions.