MICROCANONICAL THERMODYNAMICS OF FIRST-ORDER PHASE-TRANSITIONS STUDIED IN THE POTTS-MODEL

Phase transitions of first and second order can easily be distinguishe d in small systems in the microcanonical ensemble. Configurations of p hase coexistence, which are suppressed in the conventional canonical f ormulation, carry important information about the main characteristics of first order phase transitions like the transition temperature, the latent heat, and the interphase surface tension. The characteristic b ackbending of the microcanonical caloric equation of state T(E) (not t o be confused with the well known Van der Waals loops in ordinary ther modynamics or mean field approximations) leading to a negative specifi c heat is intimately linked to the interphase surface entropy.