Phase Diagram of Nuclear Matter

Nowadays it is well known that nuclear matter has a liquid and a gas phase, as well as a coexistence of phases region. Symmetric nuclear matter (same number of protons and neutrons) exhibit phase transitions from the gas phase to a liquid-gas mixture. A useful tool to represent such phases and transitions is through diagrams that show the necessary conditions of density and temperature to be in either of the phases. Now the question is, what if we extend the traditional phase diagram for symmetric matter to the asymmetric cases (different number of protons and neutrons)? This study uses classical molecular dynamics to simulate innite nuclear matter and study the effect of isospin asymmetry on bulk properties such as energy per nucleon, pressure, density, as well as the coexistence of phases region in nuclear matter. The simulations are performed on systems embedded in periodic boundary conditions with densities and temperatures in the ranges 0.01 to 0.2fm^-3 and T = 1 to 15MeV, and with isospin content of X = Z/A = 0.3, 0.35, 0.4, 0.45, and 0.5, where Z refers to the number of protons and A the total number of nucleons. The results indicate that the main effect of isospin asymmetry is found to be the disappearance of the liquid-gas phase transition when X = Z/A = 0.13. Particularly in this study, we obtain the phase diagram of nuclear matter extending it from the traditional two-dimensional density-temperature plane to three-dimensional space of density, temperature, and isospin asymmetry. We identify the liquid-gas coexistence region by means of Maxwell constructions over pressure-volume isotherms