Phase diagrams of the Hubbard liquid model

The Hubbard model is one of the most studied systems of strongly correlated electrons on the lattice. Here we propose a simple model system that generalizes the Hubbard model to an atomic liquid. Contrary to crystalline or amorphous solids where atoms are fixed, the motion of atoms in a liquid is strongly affected by the electronic structure, which in turn depends on the instantaneous ionic configuration. The Hubbard liquid model thus serves as a basic platform to investigate the nontrivial interplay between atomic dynamics and electronic correlation. Moreover, we show that the Hubbard liquid can also be viewed as a minimum model to describe the structural and electronic properties of fluid alkali metals, such as the liquid Cesium and Rubidium. We obtain the phase diagram of the Hubbard liquid model using a novel quantum molecular dynamics method in which the atomic forces are computed based on the Gutzwiller/slave-boson solution of a disordered Hubbard Hamiltonian. Characterizations of the three basic phases, the metallic cluster liquid, the dimerized insulator, and the Mott insulator, of the model are presented. We also discuss implications of our results to the metal-insulator transition in alkali liquids.