98-18E

The analysis of thermodynamic properties of the pseudospin-electron model in the case of zero electron transfer with the inclusion of the direct pseudospin-pseudospin interaction of ferroelectric type is performed. The equilibrium conditions in the regimes $\mu =const$ and $n=const$ are investigated in the mean field approximation. It is shown that the interaction with electrons leads at the fixed $\mu $ value to the possibility of the first order phase transition at the change of temperature with a jump-like behaviour of $\delimiter "426830A S^{z}\delimiter "526930B $. In the regime $n=const$ there takes place an instability with respect to phase separation in the wide range of asymmetry parameter $h$ values.