Gutzwiller approximation for a Hubbard lattice gas

We present a self-consistent Monte Carlo simulation for an ionic lattice gas coupled with electrons described by a Hubbard model with electronic hopping restricted to ions at nearest-neighbor sites. We treat a modification of our previous work, a tight-binding lattice gas model (bcc or fcc, uncorrelated electrons), to introduce two new effects: the disorder of the dense liquid metal at low temperature and, more importantly, the role of the electronic correlation. The lattice is taken to be fcc, but restricted so that an occupied site cannot have more: than eight occupied nearest neighbors. The electronic intra-atomic repulsion is included via the Gutzwiller approximation; this approach is simple enough to be solved in the large, disordered systems used in our Monte Carlo simulations but can still give a good qualitative representation of the main effects of the electronic correlations. (C) 1999 Elsevier Science B.V. All rights reserved.