Title: THE DEMIXING PHASE INSTABILITY IN THE ION-DIPOLE MIXTURE
Author(s): X.S.Chen (Institute of Theoretical Physics, Academia Sinica, P.O. Box 2735, Beijing 100080, China), F.Forstmann (Institut f\"ur Theoretische Physik, Freie Universit\"at Berlin, Arnimallee 14, D-14195 Berlin, Germany)

By considering the variation of the grand potential functional $\Omega$ with respect to small density fluctuations $\delta \rho_\alpha(1)$ we can determine the phase instability of a system from the correlation functions. Using the reference hypernetted chain (RHNC) approximation the correlation functions of an ion-dipole mixture have been calculated. With the obtained correlation functions the phase behaviour of ion-dipole mixtures has been investigated.

Key words: phase transition, demixing, instability, ion-dipole mixture, integral equations
PACS: 61.20.Gy, 64.60.-i, 64.75.+g, 64.70.-p, 64.30.+t, 61.20.Q