Lattice-gas model driven by Hubbard electrons

Self-consistent Monte Carlo simulations are undertaken for a lattice-gas mo del which is driven by the free energy of electrons described by a Hubbard model with electronic hopping restricted to ions at nearest-neighbor sites. Our previous work, an independent-electron tight-binding lattice-gas model (bcc or fee), is modified to introduce two effects: the disorder of the de nse system and, more importantly, the role of the electronic correlation. T he first effect is achieved using an fee lattice, but restricted so an occu pied site can have no more than eight, instead of twelve, occupied nearest- neighbor sites. To treat correlations, the electronic intra-atomic repulsio n is, at first, included via the Gutzwiller approximation at finite tempera ture; this approach is simple enough to be solved for all cases in the larg e, disordered systems used in our Monte Carlo simulations bur can still giv e a good qualitative representation of the main effects of the electronic c orrelations. Then, the exact treatment of the Hubbard model for clusters wi th up to six atoms is integrated into the calculation. We obtain vapor-liqu id coexistence curves and then, approximations to the electronic conductivi ties and paramagnetic susceptibilities at coexistence conditions. This simp le model is, in part, motivated by experiments on the alkali-metal fluids. [S1063-651X(99)06809-9].