MULTIBAND GUTZWILLER WAVE-FUNCTIONS FOR GENERAL ON-SITE INTERACTIONS

We introduce Gutzwiller wave functions for multiband models with gener al on-site Coulomb interactions. As these wave functions employ correl ators for the exact atomic eigenstates, they are exact both in the non interacting and atomic limits. We evaluate them in infinite lattice di mensions for all interaction strengths without any restrictions on the structure of the Hamiltonian or the symmetry of the ground state. The results for the ground-state energy allow us to derive an effective o ne-electron Hamiltonian for Landau quasiparticles, applicable for fini te temperatures and frequencies within the Fermi-liquid regime. As app lications for a two-band model we study the Brinkman-Rice metal-to-ins ulator transition at half-band-filling, and the transition to itineran t ferromagnetism for two specific fillings, at and close to a peak in the density of states of the noninteracting system. Our results signif icantly differ from those for earlier Gutzwiller wave functions where only density-type interactions were included. When the correct spin sy mmetries for the two-electron states are taken into account, the impor tance of the Hund's-rule exchange interaction is even more pronounced, and leads to paramagnetic metallic ground states with large local mag netic moments. Ferromagnetism requires fairly large interaction streng ths, and the resulting ferromagnetic state is a strongly correlated me tal.