Microcanonical Monte Carlo simulations of the first-order transition in the two-dimensional Potts model

Microcanonical Monte Carlo simulations have been implemented in the two-dim ensional (2D) q-state Potts model. The ergodicity of this simulation techni que for the Potts model is studied. It does not seem to depend on the value of q. A lack of ergodicity for small values of the system energy is report ed and discussed. It has been found that the temperature dependences of phy sical quantities exhibit an 'S'-shaped nature at the first-order transition . The degree of 'S'-shaped nature was enhanced by increasing q and reducing the system size. We believe on the basis of our computer simulations that the 'S' shape represents the equilibrium behaviour of a finite isolated sys tem.