Seminarium Fizyki Materii Skondensowanej

We analyze the transformation from insulator to metal induced by theorder-disorder phase transition within a framework of the spinlessFalicov-Kimball model. Using the Dynamic Mean Field Theory (DMFT)formalism on the Bethe lattice we find rigorously the temperaturedependent Density of States ($DOS$) at half filling in the limit of highdimensions. At zero temperature ($T=0$) the system is ordered to form thecheckerboard pattern and the $DOS$ has the gap $\Delta$ at the Fermi level$E_F=0$, which is proportional to the interaction constant $U$.Having calculated the temperature dependent $DOS$ we study thermodynamicproperties of the system starting from determination of its free energy$F$. Then we find how the order parameter $d$ and the gap $\Delta $ changewith $T$. Finally, we construct the phase diagram in the variables $T$ and$U$, where we display regions of stability of four different phases:ordered insulator, ordered metal, disordered insulator and disorderedmetal.