Hubbard model analysis with dynamical mean-field theory and selective configuration interaction*

The two-dimensional square lattice Hubbard model has been one of the most investigated Hamiltonian systems in condensed matter physics during the last few decades. Despite extensive efforts and numerous theoretical studies, there is still debate about its zero temperature phase diagram. Here, we present numerical results obtained using adaptive selected configuration interaction (ASCI) techniques for both finite size clusters and the thermodynamic limit, with the latter obtained by combining ASCI with dynamical mean-field theory (DMFT). We study basic spectral properties together with two-point correlation functions of spin and charge, for a variety of particle fillings and interaction strengths. Away from half-filling and for a wide range of interaction strengths, the finite size cluster results indicate that the ground state wave function presents a shell structure similar to that of atomic or molecular systems. In the bulk ASCI-DMFT calculations we study the effect of the bath discretization on the spectral properties.