Thermodynamics and phase transitions in two-dimensional Yukawa systems

• We have simulated strongly coupled two-dimensional Yukawa systems of particles.
• The internal energy of systems, their entropy and specific heat were calculated.
• All mentioned thermodynamic characteristics have two singular points.
• Results obtained point to the realization of the two-stage melting scenario.
• Two found phase transitions are of the second and of the first order, respectively.

The results of numerical simulations of strongly-coupled two-dimensional dissipative Yukawa systems are presented. The thermodynamic characteristics of these systems were studied, namely the internal energy, the specific heat and the entropy. For the first time, it is discovered that the considered characteristics have two singular points on the melting line; one of these points corresponds to the first-order phase transition from crystal to the hexatic phase, and another point corresponds to the second-order phase transition from the hexatic phase to the isotropic liquid. The obtained results are compared to the existing numerical and analytical data.